Remove grf_required_api_level

As we don't fix the grf window, we may not calculate the grf
expiration date and the required api level.
The verification of this will be covered by the tests at run time.

Bug: 176950752
Test: atest --host post_process_props_unittest
Change-Id: I1205f0d9a9da5bc508a49acbcbb7da581800bf45
diff --git a/tools/post_process_props.py b/tools/post_process_props.py
index 46bae29..efbf614 100755
--- a/tools/post_process_props.py
+++ b/tools/post_process_props.py
@@ -44,14 +44,12 @@
   if not prop_list.get_value("persist.sys.usb.config"):
     prop_list.put("persist.sys.usb.config", "none")
 
-def validate_and_add_grf_props(prop_list, sdk_version):
+def validate_grf_props(prop_list, sdk_version):
   """Validate GRF properties if exist.
 
   If ro.board.first_api_level is defined, check if its value is valid for the
   sdk version.
-  Also, validate the value of ro.board.api_level if defined. If the
-  ro.board.api_level property is not defined, define it with the required
-  vendor API level for the GRF policy.
+  Also, validate the value of ro.board.api_level if defined.
 
   Returns:
     True if the GRF properties are valid.
@@ -74,10 +72,6 @@
                      % (grf_api_level, sdk_version))
     return False
 
-  grf_window = 4
-  grf_required_api_level = (grf_api_level
-                  + grf_window * ((sdk_version - grf_api_level) // grf_window))
-
   if board_api_level:
     board_api_level = int(board_api_level)
     if board_api_level < grf_api_level or board_api_level > sdk_version:
@@ -86,13 +80,6 @@
                        "ro.build.version.sdk(%d)\n"
                        % (board_api_level, grf_api_level, sdk_version))
       return False
-    if board_api_level < grf_required_api_level:
-      sys.stderr.write("error: ro.board.api_level(%d) must be greater than or "
-                       "equal to %d based on GRF policy\n"
-                       % (board_api_level, grf_required_api_level))
-      return False
-  else:
-    prop_list.put("ro.board.api_level", str(grf_required_api_level))
 
   return True
 
@@ -278,7 +265,7 @@
   mangle_build_prop(props)
   if not override_optional_props(props, args.allow_dup):
     sys.exit(1)
-  if not validate_and_add_grf_props(props, args.sdk_version):
+  if not validate_grf_props(props, args.sdk_version):
     sys.exit(1)
   if not validate(props):
     sys.exit(1)