AGESA: Reduce S3_DATA_SIZE

Make some room for C environment bootblock. The S3 resume
feature needs less than 2 KiB.

Change-Id: Ic49c313d492f1d18f59d61e84f81f106e3b41fb1
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37439
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Michał Żygowski <michal.zygowski@3mdeb.com>

src/cpu/amd/agesa/Kconfig

@@ -63,7 +63,7 @@ config S3_DATA_POS
 
 config S3_DATA_SIZE
 	int
-	default 32768
+	default 8192
 
 endif # CPU_AMD_AGESA