Change checkpatch.pl tab expanding to 4 characters.

The C coding style guide says that tab width is 4 characters but checkpatch.pl expands tabs to 8 characters which produces false negatives.

Change-Id: Ibdabbb55269b7cf6bcd38042cccb8bd235e42ce2
Signed-off-by: Erik Ahlén <erik.ahlen@avalonenterprise.com>
Reviewed-on: http://openocd.zylin.com/275
Tested-by: jenkins
Reviewed-by: Øyvind Harboe <oyvindharboe@gmail.com>
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

tools/scripts/checkpatch.pl

@@ -504,7 +504,7 @@ sub expand_tabs {
 		if ($c eq "\t") {
 			$res .= ' ';
 			$n++;
-			for (; ($n % 8) != 0; $n++) {
+			for (; ($n % 4) != 0; $n++) {
 				$res .= ' ';
 			}
 			next;