cbfs: Add metadata cache

This patch adds a new CBFS "mcache" (metadata cache) -- a memory buffer
that stores the headers of all CBFS files. Similar to the existing FMAP
cache, this cache should reduce the amount of SPI accesses we need to do
every boot: rather than having to re-read all CBFS headers from SPI
flash every time we're looking for a file, we can just walk the same
list in this in-memory copy and finally use it to directly access the
flash at the right position for the file data.

This patch adds the code to support the cache but doesn't enable it on
any platform. The next one will turn it on by default.

Change-Id: I5b1084bfdad1c6ab0ee1b143ed8dd796827f4c65
Signed-off-by: Julius Werner <jwerner@chromium.org>
---
M src/commonlib/Makefile.inc
A src/commonlib/bsd/cbfs_mcache.c
M src/commonlib/bsd/include/commonlib/bsd/cb_err.h
M src/commonlib/bsd/include/commonlib/bsd/cbfs_private.h
M src/commonlib/include/commonlib/cbmem_id.h
M src/include/cbfs.h
M src/include/memlayout.h
M src/include/symbols.h
M src/lib/Kconfig
M src/lib/cbfs.c
M src/lib/coreboot_table.c
M src/security/vboot/vboot_common.h
M src/security/vboot/vboot_loader.c
13 files changed, 357 insertions(+), 34 deletions(-)