checkpatch: check stable email address

It should be stable@vger.kernel.org, not stable@kernel.org.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -1944,6 +1944,12 @@ sub process {
 			}
 		}
 
+# Check for old stable address
+		if ($line =~ /^\s*cc:\s*.*<?\bstable\@kernel\.org\b>?.*$/i) {
+			ERROR("STABLE_ADDRESS",
+			      "The 'stable' address should be 'stable\@vger.kernel.org'\n" . $herecurr);
+		}
+
 # Check for unwanted Gerrit info
 		if ($in_commit_log && $line =~ /^\s*change-id:/i) {
 			ERROR("GERRIT_CHANGE_ID",