checkpatch: enable whitespace checks for DTS files

When run on *.dtsi or *.dts files, the whitespace checks were skipped,
while they are valid for DTS files.  Hence stop skipping them.

I ran checkpatch on all in-tree DTS files, and didn't notice any error or
warning messages that are inappropriate for DTS files.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -2343,7 +2343,7 @@ sub process {
 		}
 
 # check we are in a valid source file if not then ignore this hunk
-		next if ($realfile !~ /\.(h|c|s|S|pl|sh)$/);
+		next if ($realfile !~ /\.(h|c|s|S|pl|sh|dtsi|dts)$/);
 
 #line length limit
 		if ($line =~ /^\+/ && $prevrawline !~ /\/\*\*/ &&
@@ -2404,7 +2404,7 @@ sub process {
 		}
 
 # check we are in a valid source file C or perl if not then ignore this hunk
-		next if ($realfile !~ /\.(h|c|pl)$/);
+		next if ($realfile !~ /\.(h|c|pl|dtsi|dts)$/);
 
 # at the beginning of a line any tabs must come first and anything
 # more than 8 must use tabs.