Revert "Android.mk: Enforce SYSTEM_EXT_* vars on API >= 31"

This reverts commit 6c99a6781cee1bad995919d3156d7c799f59317c.

Reason for revert: build breaks on build test
Bug: 171847597
Test: None

Change-Id: I7d3556aa0f06684b43f80f09e4c8194c6c44336c
diff --git a/Android.mk b/Android.mk
index 960b8f8..111ddd9 100644
--- a/Android.mk
+++ b/Android.mk
@@ -55,21 +55,12 @@
 
 SYSTEM_EXT_PUBLIC_POLICY := $(SYSTEM_EXT_PUBLIC_SEPOLICY_DIRS)
 ifneq (,$(BOARD_PLAT_PUBLIC_SEPOLICY_DIR))
-  # Must use new variable name for devices launched on S
-  ifdef PRODUCT_SHIPPING_API_LEVEL
-    ifneq ($(call math_gt_or_eq,$(PRODUCT_SHIPPING_API_LEVEL),31),)
-      $(error Please use SYSTEM_EXT_PUBLIC_SEPOLICY_DIRS instead of the old variable BOARD_PLAT_PUBLIC_SEPOLICY_DIR)
-    endif
-  endif
+  # TODO: Disallow BOARD_PLAT_*
   SYSTEM_EXT_PUBLIC_POLICY += $(BOARD_PLAT_PUBLIC_SEPOLICY_DIR)
 endif
 SYSTEM_EXT_PRIVATE_POLICY := $(SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS)
 ifneq (,$(BOARD_PLAT_PRIVATE_SEPOLICY_DIR))
-  ifdef PRODUCT_SHIPPING_API_LEVEL
-    ifneq ($(call math_gt_or_eq,$(PRODUCT_SHIPPING_API_LEVEL),31),)
-      $(error Please use SYSTEM_EXT_PRIVATE_SEPOLICY_DIRS instead of the old variable BOARD_PLAT_PRIVATE_SEPOLICY_DIR)
-    endif
-  endif
+  # TODO: Disallow BOARD_PLAT_*
   SYSTEM_EXT_PRIVATE_POLICY += $(BOARD_PLAT_PRIVATE_SEPOLICY_DIR)
 endif