amd/stoneyridge: Add BIOS RAM R/W functions

The internal FCH contains 256 bytes of "BiosRam" that maintains its
state until RSMRST# is asserted or standby power is lost.  Add functions
to support read and write operations.

Change-Id: I2ddf58a63e69b2775de9a8163534b13dad2ea2fe
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/22724
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Richard Spiegel <richard.spiegel@silverbackltd.com>
2 files changed