mb/google/brya: Compile gpio.c in SMM when needed

Without gpio.c compiled in, SMMSTORE will fail to initialize and hang.
Add a conditional inclusion so gpio.c is compiled in SMM when SMMSTORE
is selected.

TEST=build/boot google/banshee with SMMSTORE support enabled

Change-Id: If049cba98f13f060807058029306dcad2ada2d49
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/74233
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tarun Tuli <taruntuli@google.com>

src/mainboard/google/brya/variants/baseboard/brask/Makefile.inc

@@ -5,3 +5,5 @@ romstage-y += gpio.c
 
 ramstage-y += gpio.c
 ramstage-y += ramstage.c
+
+smm-$(CONFIG_SMMSTORE) += gpio.c

src/mainboard/google/brya/variants/baseboard/brya/Makefile.inc

@@ -5,3 +5,5 @@ romstage-y += gpio.c
 
 ramstage-y += gpio.c
 ramstage-y += ramstage.c
+
+smm-$(CONFIG_SMMSTORE) += gpio.c

src/mainboard/google/brya/variants/baseboard/nissa/Makefile.inc

@@ -5,3 +5,5 @@ romstage-y += gpio.c
 
 ramstage-y += gpio.c
 ramstage-y += ramstage.c
+
+smm-$(CONFIG_SMMSTORE) += gpio.c