mb/google/rex: Dump ISH version for `rex_ec_ish` variant

This patch selects `SOC_INTEL_STORE_ISH_FW_VERSION` config to dump
the ISH version as part of the .final hook.

BUG=b:285405031
TEST=Able to build and boot google/rex_ec_ish. Verify the ISH version
is same as MFIT ISH version section.

> cbmem -c | grep "ISH"
  [DEBUG]  ISH version: 5.6.0.28821

Change-Id: I052af85ad836ab81ff6c510bb74e042b11940a65
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/77178
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-by: Dinesh Gehlot <digehlot@google.com>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/mainboard/google/rex/Kconfig.name b/src/mainboard/google/rex/Kconfig.name
index 89255b3..fc9a477 100644
--- a/src/mainboard/google/rex/Kconfig.name
+++ b/src/mainboard/google/rex/Kconfig.name
@@ -23,6 +23,7 @@
 config BOARD_GOOGLE_REX_EC_ISH
 	bool "-> Rex EC ISH"
 	select BOARD_GOOGLE_MODEL_REX
+	select SOC_INTEL_STORE_ISH_FW_VERSION
 
 config BOARD_GOOGLE_OVIS
 	bool "-> Ovis"