checkpatch: warn when a MAINTAINERS entry isn't [A-Z]:\t

For consistency, MAINTAINERS entries should be an upper case letter, then
a colon, then a tab, then the value.

Warn when an entry doesn't have this form.  --fix it too.

Link: http://lkml.kernel.org/r/9aaaf03ec10adf3888b5e98dd2176b7fe9b5fad8.1496343345.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

scripts/checkpatch.pl

@@ -2775,6 +2775,17 @@ sub process {
 			#print "is_start<$is_start> is_end<$is_end> length<$length>\n";
 		}
 
+# check for MAINTAINERS entries that don't have the right form
+		if ($realfile =~ /^MAINTAINERS$/ &&
+		    $rawline =~ /^\+[A-Z]:/ &&
+		    $rawline !~ /^\+[A-Z]:\t\S/) {
+			if (WARN("MAINTAINERS_STYLE",
+				 "MAINTAINERS entries use one tab after TYPE:\n" . $herecurr) &&
+			    $fix) {
+				$fixed[$fixlinenr] =~ s/^(\+[A-Z]):\s*/$1:\t/;
+			}
+		}
+
 # discourage the use of boolean for type definition attributes of Kconfig options
 		if ($realfile =~ /Kconfig/ &&
 		    $line =~ /^\+\s*\bboolean\b/) {