npem: fix false positive in permission check

Sometimes when a permission is not granted (e.g. when a default permission
to a system app is ungranted by the user), dumpsys emits two lines about
it, one with granted=true and the GRANTED_BY_DEFAULT flag.

Since we are not properly parsing flags and getting the full context, just
reverse the check to make sure the value doesn't fall through.

A 'false negative' grant won't hurt anyway.

res/system/bin/npem

@@ -39,7 +39,7 @@ check_package () {
 }
 
 check_permission () {
-	[[ $(dumpsys package ${1} | grep -Eo "^[ ]+${2}: granted=true") ]] && return 0 || return 1
+	[[ $(dumpsys package ${1} | grep -Eo "^[ ]+${2}: granted=false") ]] && return 1 || return 0
 }
 
 grant_permission () {