nb/intel/i945: Put stage cache in TSEG

TSEG is not accessible in ring 0 after it is locked in ramstage, in
contrast with cbmem which remains accessible. Assuming SMM does not
touch the cache this is a good region to cache stages.

Tested on Intel D945GCLF and Lenovo Thinkpad X60, on cold boot the
external stage cache gets created and the stage cache gets properly
used on S3 resume.

Change-Id: I447815bb0acf5f8e53834b74785d496f9d4df1da
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/25603
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/northbridge/intel/i945/Kconfig b/src/northbridge/intel/i945/Kconfig
index 996e1d9..2c21420 100644
--- a/src/northbridge/intel/i945/Kconfig
+++ b/src/northbridge/intel/i945/Kconfig
@@ -31,6 +31,7 @@
 	select POSTCAR_CONSOLE
 	select SMM_TSEG
 	select PARALLEL_MP
+	select CACHE_RELOCATED_RAMSTAGE_OUTSIDE_CBMEM
 
 config NORTHBRIDGE_INTEL_SUBTYPE_I945GC
 	def_bool n
@@ -90,4 +91,8 @@
 	  On other boards the check always creates a false positive,
 	  effectively making it impossible to resume.
 
+config SMM_RESERVED_SIZE
+	hex
+	default 0x100000
+
 endif