post_code: add post code for memory error

Add a new post code POST_RAM_FAILURE, used when the Intel FSP code fails
to initialize RAM.

BUG=b:124401932
BRANCH=sarien
TEST=build coreboot for sarien and arcada platforms

Change-Id: Ibafefa0fc0b1c525f923929cc91731fbcc1e7533
Signed-off-by: Keith Short <keithshort@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32773
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
diff --git a/Documentation/POSTCODES b/Documentation/POSTCODES
index 855940f..2a8285b 100644
--- a/Documentation/POSTCODES
+++ b/Documentation/POSTCODES
@@ -19,6 +19,7 @@
 0xe0 Boot media (e.g. SPI ROM) is corrupt
 0xe1 Resource stored within CBFS is corrupt
 0xe2 Vendor binary (e.g. FSP) generated a fatal error
+0xe3 RAM could not be initialized
 0xf8 Entry into elf boot
 0xf3 Jumping to payload