checkpatch: silence perl 5.26.0 unescaped left brace warnings

As of perl 5, version 26, subversion 0 (v5.26.0) some new warnings have
occurred when running checkpatch.

Unescaped left brace in regex is deprecated here (and will be fatal in
Perl 5.30), passed through in regex; marked by <-- HERE in m/^(.\s*){
<-- HERE \s*/ at scripts/checkpatch.pl line 3544.

Unescaped left brace in regex is deprecated here (and will be fatal in
Perl 5.30), passed through in regex; marked by <-- HERE in m/^(.\s*){
<-- HERE \s*/ at scripts/checkpatch.pl line 3885.

Unescaped left brace in regex is deprecated here (and will be fatal in
Perl 5.30), passed through in regex; marked by <-- HERE in
m/^(\+.*(?:do|\))){ <-- HERE / at scripts/checkpatch.pl line 4374.

It seems perfectly reasonable to do as the warning suggests and simply
escape the left brace in these three locations.

Link: http://lkml.kernel.org/r/20170607060135.17384-1-cyrilbur@gmail.com
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Acked-by: Joe Perches <joe@perches.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -3555,7 +3555,7 @@ sub process {
 				$fixedline =~ s/\s*=\s*$/ = {/;
 				fix_insert_line($fixlinenr, $fixedline);
 				$fixedline = $line;
-				$fixedline =~ s/^(.\s*){\s*/$1/;
+				$fixedline =~ s/^(.\s*)\{\s*/$1/;
 				fix_insert_line($fixlinenr, $fixedline);
 			}
 		}
@@ -3896,7 +3896,7 @@ sub process {
 				my $fixedline = rtrim($prevrawline) . " {";
 				fix_insert_line($fixlinenr, $fixedline);
 				$fixedline = $rawline;
-				$fixedline =~ s/^(.\s*){\s*/$1\t/;
+				$fixedline =~ s/^(.\s*)\{\s*/$1\t/;
 				if ($fixedline !~ /^\+\s*$/) {
 					fix_insert_line($fixlinenr, $fixedline);
 				}
@@ -4385,7 +4385,7 @@ sub process {
 			if (ERROR("SPACING",
 				  "space required before the open brace '{'\n" . $herecurr) &&
 			    $fix) {
-				$fixed[$fixlinenr] =~ s/^(\+.*(?:do|\))){/$1 {/;
+				$fixed[$fixlinenr] =~ s/^(\+.*(?:do|\)))\{/$1 {/;
 			}
 		}