soc/amd/common/block/spi: Mainboard to override SPI Read Mode

On certain mainboards due to hardware design limitations, certain SPI
Read Modes eg. (Dual I/O 1-2-2) cannot be supported. Add ability to
override SPI read modes in boards which do not have hardware
limitations. Currently there is an API to override SPI fast speeds.
Update this API for mainboards to override SPI read mode as well.

BUG=b:225213679
TEST=Build and boot to OS in Skyrim. Observe a boot time improvement of
~25 ms with 100 MHz SPI speeds.
Before:
  11:start of bootblock                                688,046
  14:finished loading romstage                         30,865
  16:FSP-M finished LZMA decompress (ignore for x86)   91,049
Total Time: 1,972,625

After:
  11:start of bootblock                                667,642
  14:finished loading romstage                         29,798
  16:FSP-M finished LZMA decompress (ignore for x86)   87,743
Total Time: 1,943,924

Change-Id: I160b56f6201a798ce59e977ca40301e23ab63805
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/68946
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jon Murphy <jpmurphy@google.com>

0 files changed, 0 insertions, 0 deletions