sepolicy: Only include legacy QC sepolicy

 * This has now turned into a separate repository (maintained only
   for legacy devices, those that never got official Oreo updates).

Change-Id: I981b452b697bc3610d7aa97b74ed182c6b70ca30

board/selinux.mk

@@ -1,3 +1,6 @@
+# QCOM legacy sepolicies
+include device/qcom/sepolicy-legacy/sepolicy.mk
+
 # Device sepolicies
 BOARD_SEPOLICY_DIRS += \
     $(DEVICE_PATH)/sepolicy