kernel-doc: Fix up warning output

While trying to make gpu docs warning free I stumbled over one output
which wasn't following proper compiler error output standards. Fix it
up for more quickfix awesomeness.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

scripts/kernel-doc

@@ -2994,7 +2994,7 @@ sub process_file($) {
 		    }
 		} elsif ($inline_doc_state == STATE_INLINE_NAME) {
 		    $inline_doc_state = STATE_INLINE_ERROR;
-		    print STDERR "Warning(${file}:$.): ";
+		    print STDERR "${file}:$.: warning: ";
 		    print STDERR "Incorrect use of kernel-doc format: $_";
 		    ++$warnings;
 		}