checkpatch: allow space between colon and bracket

Allow a space between a colon and subsequent opening bracket.  This
sequence may occur in inline assembler statements like

	asm(
		"ldr %[out], [%[in]]\n\t"
		: [out] "=r" (ret)
		: [in] "r" (addr)
	);

Link: http://lkml.kernel.org/r/20180403191655.23700-1-xypron.glpk@gmx.de
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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

@@ -4089,7 +4089,7 @@ sub process {
 			my ($where, $prefix) = ($-[1], $1);
 			if ($prefix !~ /$Type\s+$/ &&
 			    ($where != 0 || $prefix !~ /^.\s+$/) &&
-			    $prefix !~ /[{,]\s+$/) {
+			    $prefix !~ /[{,:]\s+$/) {
 				if (ERROR("BRACKET_SPACE",
 					  "space prohibited before open square bracket '['\n" . $herecurr) &&
 				    $fix) {