soc/amd/picasso: Create a hybrid romstage to begin in DRAM

Add the support files to begin execution in romstage and located in
DRAM.  Details for this implementation are found in
Documentation/amd/picasso/family17.md.

Combine steps typically found in bootblock, containing the reset
vector and protected mode enable, with the parts of romstage
that enable the console and cbmem.

Duplicate the ROMSTAGE_ADDR and ROMSTAGE_MAX_SIZE items into Kconfig
and give them safe default values in DRAM.  The DCACHE values are
kept and DRAM is used as a CAR substitute.

Add a romstage.ld file that positions the reset vector and describes
the additional items needed for the hybrid romstage.

Change-Id: Id8c6175de34a0728ad41085e9c7cd310bd280976
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
---
M src/soc/amd/picasso/Kconfig
M src/soc/amd/picasso/Makefile.inc
M src/soc/amd/picasso/include/soc/cpu.h
M src/soc/amd/picasso/include/soc/romstage.h
A src/soc/amd/picasso/include/soc/romstage.ld
A src/soc/amd/picasso/reset_vector.S
M src/soc/amd/picasso/romstage.c
7 files changed, 400 insertions(+), 72 deletions(-)