sb/intel/common/smihandler: Hook up smmstore

TESTED on Asus P5QC.

Change-Id: I20b87f3dcb898656ad31478820dd5153e4053cb2
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/30012
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/southbridge/intel/common/Kconfig b/src/southbridge/intel/common/Kconfig
index c3bd90d..dfd8975 100644
--- a/src/southbridge/intel/common/Kconfig
+++ b/src/southbridge/intel/common/Kconfig
@@ -20,6 +20,7 @@
 config SOUTHBRIDGE_INTEL_COMMON_SPI
 	def_bool n
 	select SPI_FLASH
+	select BOOT_DEVICE_SUPPORTS_WRITES
 
 config SOUTHBRIDGE_INTEL_COMMON_PIRQ_ACPI_GEN
 	def_bool n