feat(mt8188): initialize GIC

Initialize GIC for mt8188.

TEST=build pass
BUG=b:236331724

Change-Id: I5acf77d654f1bbce32e9fbb3f3567600b7db10ed
diff --git a/plat/mediatek/mt8188/platform.mk b/plat/mediatek/mt8188/platform.mk
index 08cebf0..82c4ce1 100644
--- a/plat/mediatek/mt8188/platform.mk
+++ b/plat/mediatek/mt8188/platform.mk
@@ -22,6 +22,7 @@
 MODULES-y += $(MTK_PLAT)/common
 MODULES-y += $(MTK_PLAT)/lib/mtk_init
 MODULES-y += $(MTK_PLAT)/lib/pm
+MODULES-y += $(MTK_PLAT)/drivers/gic600
 MODULES-y += $(MTK_PLAT)/drivers/timer
 
 PLAT_BL_COMMON_SOURCES := common/desc_image_load.c \