checkpatch: check compatible strings in .c and .h too

Look for ".compatible = "foo" strings not only in .dts files, but
in .c and .h too.
Signed-off-by: Florian Vaussard <florian.vaussard@epfl.ch>
Cc: Joe Perches <joe@perches.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -2074,8 +2074,10 @@ sub process {
 		}
 
 # check for DT compatible documentation
-		if (defined $root && $realfile =~ /\.dts/ &&
-		    $rawline =~ /^\+\s*compatible\s*=/) {
+		if (defined $root &&
+			(($realfile =~ /\.dtsi?$/ && $line =~ /^\+\s*compatible\s*=\s*\"/) ||
+			 ($realfile =~ /\.[ch]$/ && $line =~ /^\+.*\.compatible\s*=\s*\"/))) {
+
 			my @compats = $rawline =~ /\"([a-zA-Z0-9\-\,\.\+_]+)\"/g;
 
 			foreach my $compat (@compats) {