soc/intel/braswell: select GENERIC_GPIO_LIB

Needed for to-be-added Google Braswell boards which make use
of common GPIO library function to determine installed RAM type.

Change-Id: Ie9b0c6513f10b252bf0a5014bd038d24879421be
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/21125
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/braswell/Kconfig

@@ -47,6 +47,7 @@ config CPU_SPECIFIC_OPTIONS
 	select HAVE_INTEL_FIRMWARE
 	select HAVE_SPI_CONSOLE_SUPPORT
 	select HAVE_FSP_GOP
+	select GENERIC_GPIO_LIB
 
 config VBOOT
 	select VBOOT_STARTS_IN_ROMSTAGE