feat(mt8188): add LPM driver support

Add LPM drivers and create rules.mk for makefile.

Change-Id: I0bfb99a4a763e7ca93260f62d1ced184259acb39
diff --git a/plat/mediatek/mt8188/platform.mk b/plat/mediatek/mt8188/platform.mk
index 84bcfac..a50f750 100644
--- a/plat/mediatek/mt8188/platform.mk
+++ b/plat/mediatek/mt8188/platform.mk
@@ -27,6 +27,7 @@
 MODULES-y += $(MTK_PLAT)/drivers/gic600
 MODULES-y += $(MTK_PLAT)/drivers/gpio
 MODULES-y += $(MTK_PLAT)/drivers/iommu
+MODULES-y += $(MTK_PLAT)/drivers/lpm
 MODULES-y += $(MTK_PLAT)/drivers/pmic
 MODULES-y += $(MTK_PLAT)/drivers/pmic_wrap
 MODULES-y += $(MTK_PLAT)/drivers/rtc