mb/google/brya/var/{taeko, taeko4es}: Add gpio.c in romstage

Add file gpio.c in romstage.

BUG=b:213828931
TEST=Build FW and system can power on normally.

Signed-off-by: Kevin Chang <kevin.chang@lcfc.corp-partner.google.com>
Change-Id: Ie868fe7ada9deb8918d6c7ba538332cbe539ee44
Reviewed-on: https://review.coreboot.org/c/coreboot/+/61173
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: YH Lin <yueherngl@google.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

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

@@ -1,5 +1,7 @@
 bootblock-y += gpio.c
 
+romstage-y += gpio.c
+
 romstage-y += memory.c
 
 ramstage-y += gpio.c

src/mainboard/google/brya/variants/taeko4es/Makefile.inc

@@ -1,5 +1,7 @@
 bootblock-y += gpio.c
 
+romstage-y += gpio.c
+
 romstage-y += memory.c
 
 ramstage-y += gpio.c