wtm2: auto-select CACHE_ROM

The WTM2 board has a fairly static configuration. As such
it's been tested to properly handle CACHE_ROM given the number
of MTRRs the boards' CPUs supports.

Change-Id: Ic67cd1eebce580003dc6b6655cac2b2a92dd1b5f
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/2964
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/mainboard/intel/wtm2/Kconfig

@@ -16,6 +16,7 @@ config BOARD_SPECIFIC_OPTIONS # dummy
 	select HAVE_SMI_HANDLER
 	select CHROMEOS
 	select EXTERNAL_MRC_BLOB
+	select CACHE_ROM
 
 config MAINBOARD_DIR
 	string