sb/intel/common: Add SOUTHBRIDGE_INTEL_COMMON_SPI

This introduces a Kconfig option to include common Intel SPI code.

Change-Id: I970408e5656c0e8812b8609e2cc10d0bc8d8f6f2
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/21674
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>

src/southbridge/intel/common/Kconfig

@@ -8,6 +8,10 @@ config SOUTHBRIDGE_INTEL_COMMON_SMBUS
 	def_bool n
 	select HAVE_DEBUG_SMBUS
 
+config SOUTHBRIDGE_INTEL_COMMON_SPI
+	def_bool n
+	select SPI_FLASH
+
 config HAVE_INTEL_CHIPSET_LOCKDOWN
 	def_bool n