Change in coreboot[master]: soc/amd/common/apob: Add support for asynchronously reading APOB_NV

[Raul Rangel (Code Review)]

Attention is currently required from: Jason Glenesk, Marshall Dawson, Felix Held.
Hello build bot (Jenkins), Jason Glenesk, Marshall Dawson, Eric Peers, Felix Held,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/56232

to look at the new patch set (#4).

Change subject: soc/amd/common/apob: Add support for asynchronously reading APOB_NV
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soc/amd/common/apob: Add support for asynchronously reading APOB_NV

This CL adds a method that can start the processes of reading the APOB
from SPI. It does require more RAM in ramstage since we no longer mmap
the buffer in the happy path. This will allow us to reduce our
boot time by ~10ms. The SoC code will need to be updated to call 
start_apob_cache_read at a point where it makes sense.

BUG=b:179699789
TEST=With this and the patches above I can see a 10 ms reduction in
boot time on guybrush.

Signed-off-by: Raul E Rangel 
Change-Id: I930d58b76eb4558bc4f48ed928c4d6538fefb1e5
---
M src/soc/amd/common/block/apob/apob_cache.c
M src/soc/amd/common/block/include/amdblocks/apob_cache.h
2 files changed, 65 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/32/56232/4