arch/x86: Implement RESET_VECTOR_IN_RAM for bootblock

Add support for devices with the reset vector pointing into DRAM.  This
is a specific implementation that assumes a paradigm of AMD Family 17h
(a.k.a. "Zen").  Until the first ljmpl for protected mode, the core's
state appears to software like other designs, and then the actual
physical addressing becomes recognizable.

Due the nature of a system where the DRAM is alive before the x86, a
number of design options were considered, including the first stage as
ramstage.  Beginning with ramstage was infeasible because the processor
must still go through the typical initial steps and be put into flat
protected mode.

This patch is phase 1 of adding support and it builds a traditional
bootblock image.  Although running from DRAM, the unused bootblock
is kept in cbfs.  The details for placing the bootblock into memory
are left to the soc implementation.

Sample build using amd/mandolin (currently WIP):
  Name                           Offset     Type           Size   Comp
  cbfs master header             0x0        cbfs header        32 none
  fallback/romstage              0x80       stage           21300 none
  fallback/ramstage              0x5440     stage           76115 none
  config                         0x17e00    raw               398 none
  revision                       0x18000    raw               674 none
  payload_config                 0x18300    raw              1593 none
  payload_revision               0x18980    raw               262 none
  (empty)                        0x18b00    null              664 none
  fspm.bin                       0x18dc0    fsp            786432 none
  (empty)                        0xd8e00    null             3992 none
  fsps.bin                       0xd9dc0    fsp            262144 none
  pci1002,15d8.rom               0x119e00   optionrom       54272 none
  fallback/dsdt.aml              0x127280   raw              8365 none
  fallback/payload               0x129380   simple elf      68099 none
  (empty)                        0x139dc0   null          2383832 none
  bootblock                      0x37fdc0   bootblock      524288 none

readelf of build/cbfs/fallback/bootblock.elf:
Section Headers:
  [Nr] Name              Type      Addr     Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL      00000000 000000 000000 00      0   0  0
  [ 1] .text             PROGBITS  02000000 000060 005318 00  AX  0   0 32
  [ 2] .rel.text         REL       00000000 006f34 0010d8 08   I  5   1  4
  [ 3] .earlyram.data    NOBITS    0802d000 000000 045ed8 00  WA  0   0 32
  [ 4] .gnu_debuglink    PROGBITS  00000000 005378 000014 00      0   0  4
  [ 5] .symtab           SYMTAB    00000000 00538c 000e50 10      6  61  4
  [ 6] .strtab           STRTAB    00000000 0061dc 000d57 00      0   0  1
  [ 7] .shstrtab         STRTAB    00000000 00800c 000043 00      0   0  1

 91: 0802d000     0 NOTYPE  GLOBAL DEFAULT    3 _earlyram_stack
 68: 0802d800     0 NOTYPE  GLOBAL DEFAULT    3 _eearlyram_stack
175: 0802d800     0 NOTYPE  GLOBAL DEFAULT    3 _preram_cbmem_console
199: 0802ee00     0 NOTYPE  GLOBAL DEFAULT    3 _epreram_cbmem_console
120: 0802ee00     0 NOTYPE  GLOBAL DEFAULT    3 _timestamp
221: 0802f000     0 NOTYPE  GLOBAL DEFAULT    3 _etimestamp
153: 0802f000     0 NOTYPE  GLOBAL DEFAULT    3 _bss
130: 08072ed8     0 NOTYPE  GLOBAL DEFAULT    3 _ebss

Change-Id: I9c084ff6fdcf7e9154436f038705e8679daea780
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
---
M Makefile.inc
M src/arch/x86/Kconfig
M src/arch/x86/assembly_entry.S
A src/arch/x86/early_ram.ld
M src/arch/x86/memlayout.ld
M src/cpu/Kconfig
M src/include/memlayout.h
7 files changed, 79 insertions(+), 5 deletions(-)