sepolicy: using SYSTEM_EXT_<PUBLIC/PRIVATE>_SEPOLICY_DIRS variable

BOARD_PLAT_<PUBLIC/PRIVATE>SEPOLICY_DIR is going to be deprecated
so using new flag.

Change-Id: I039e81ca3bced08038f0e7f2ea3e706947d024fb
diff --git a/SEPolicy.mk b/SEPolicy.mk
index 445df9f..39584d8 100644
--- a/SEPolicy.mk
+++ b/SEPolicy.mk
@@ -1,22 +1,22 @@
 # Board specific SELinux policy variable definitions
 ifeq ($(call is-vendor-board-platform,QCOM),true)
 SEPOLICY_PATH:= device/qcom/sepolicy
-BOARD_PLAT_PUBLIC_SEPOLICY_DIR := \
-    $(BOARD_PLAT_PUBLIC_SEPOLICY_DIR) \
+SYSTEM_EXT_PUBLIC_SEPOLICY_DIRS := \
+    $(SYSTEM_EXT_PUBLIC_SEPOLICY_DIRS) \
     $(SEPOLICY_PATH)/generic/public \
     $(SEPOLICY_PATH)/generic/public/attribute
 
-BOARD_PLAT_PRIVATE_SEPOLICY_DIR := \
-    $(BOARD_PLAT_PRIVATE_SEPOLICY_DIR) \
+SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS := \
+    $(SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS) \
     $(SEPOLICY_PATH)/generic/private
 
-BOARD_PLAT_PUBLIC_SEPOLICY_DIR := \
-    $(BOARD_PLAT_PUBLIC_SEPOLICY_DIR) \
+SYSTEM_EXT_PUBLIC_SEPOLICY_DIRS := \
+    $(SYSTEM_EXT_PUBLIC_SEPOLICY_DIRS) \
     $(SEPOLICY_PATH)/qva/public \
     $(SEPOLICY_PATH)/qva/public/attribute
 
-BOARD_PLAT_PRIVATE_SEPOLICY_DIR := \
-    $(BOARD_PLAT_PRIVATE_SEPOLICY_DIR) \
+SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS := \
+    $(SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS) \
     $(SEPOLICY_PATH)/qva/private
 
 #once all the services are moved to Product /ODM above lines will be removed.