sepolicy: Switch to SYSTEM_EXT_{PUBLIC,PRIVATE}_SEPOLICY_DIRS

Fixes:
warning: BOARD_PLAT_PRIVATE_SEPOLICY_DIR has been deprecated.
    Use SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS instead.
warning: BOARD_PLAT_PUBLIC_SEPOLICY_DIR has been deprecated.
    Use SYSTEM_EXT_PUBLIC_SEPOLICY_DIRS instead.
Change-Id: I752602079de8ff4c5370fe3ec861b8746838d878
diff --git a/exynos/sepolicy.mk b/exynos/sepolicy.mk
index c34274e..fd25f4e 100644
--- a/exynos/sepolicy.mk
+++ b/exynos/sepolicy.mk
@@ -9,11 +9,11 @@
 endif
 endif
 
-BOARD_PLAT_PRIVATE_SEPOLICY_DIR += \
+SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS += \
     device/lineage/sepolicy/exynos/private
 
 ifeq ($(TARGET_USES_PREBUILT_VENDOR_SEPOLICY), true)
-BOARD_PLAT_PRIVATE_SEPOLICY_DIR += \
+SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS += \
     device/lineage/sepolicy/exynos/dynamic \
     device/lineage/sepolicy/exynos/system
 else