feat(mt8188): add armv8.2 support

Add armv8.2 support for MT8188.

Change-Id: I0ac865949ba864fb207ee1f0937092cbabd550de
diff --git a/plat/mediatek/mt8188/plat_config.mk b/plat/mediatek/mt8188/plat_config.mk
index a69ea96..169f776 100644
--- a/plat/mediatek/mt8188/plat_config.mk
+++ b/plat/mediatek/mt8188/plat_config.mk
@@ -32,5 +32,6 @@
 ERRATA_A78_2376745 := 1
 ERRATA_A78_2395406 := 1
 
+CONFIG_ARCH_ARM_V8_2 := y
 MACH_MT8188 := 1
 $(eval $(call add_define,MACH_MT8188))