lint/checkpatch.pl: escape \{ in perl regex to fix warnings

Fix warnings:
Unescaped left brace in regex is deprecated, passed through in regex;
marked by <-- HERE in m/\#\s*define.*do\s{ <-- HERE / at util/lint/checkpatch.pl line 3261.
marked by <-- HERE in m/\(.*\){ <-- HERE / at util/lint/checkpatch.pl line 3750.
marked by <-- HERE in m/do{ <-- HERE / at util/lint/checkpatch.pl line 3751.
marked by <-- HERE in m/^\({ <-- HERE / at util/lint/checkpatch.pl line 4194.

Change-Id: If0c1f07a16df9e6cd1c1393a31af8b8ea6a66b01
Signed-off-by: Alexander Couzens <lynxis@fe80.eu>
Reviewed-on: https://review.coreboot.org/14310
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
diff --git a/util/lint/checkpatch.pl b/util/lint/checkpatch.pl
index 894e5d7..3a4b8be 100755
--- a/util/lint/checkpatch.pl
+++ b/util/lint/checkpatch.pl
@@ -3258,7 +3258,7 @@
 # function brace can't be on same line, except for #defines of do while,
 # or if closed on same line
 		if (($line=~/$Type\s*$Ident\(.*\).*\s*{/) and
-		    !($line=~/\#\s*define.*do\s{/) and !($line=~/}/)) {
+		    !($line=~/\#\s*define.*do\s\{/) and !($line=~/}/)) {
 			if (ERROR("OPEN_BRACE",
 				  "open brace '{' following function declarations go on the next line\n" . $herecurr) &&
 			    $fix) {
@@ -3747,8 +3747,8 @@
 ## 		}
 
 #need space before brace following if, while, etc
-		if (($line =~ /\(.*\){/ && $line !~ /\($Type\){/) ||
-		    $line =~ /do{/) {
+		if (($line =~ /\(.*\)\{/ && $line !~ /\($Type\)\{/) ||
+		    $line =~ /do\{/) {
 			if (ERROR("SPACING",
 				  "space required before the open brace '{'\n" . $herecurr) &&
 			    $fix) {
@@ -4190,8 +4190,8 @@
 			    $dstat !~ /^do\s*$Constant\s*while\s*$Constant;?$/ &&	# do {...} while (...); // do {...} while (...)
 			    $dstat !~ /^for\s*$Constant$/ &&				# for (...)
 			    $dstat !~ /^for\s*$Constant\s+(?:$Ident|-?$Constant)$/ &&	# for (...) bar()
-			    $dstat !~ /^do\s*{/ &&					# do {...
-			    $dstat !~ /^\({/ &&						# ({...
+			    $dstat !~ /^do\s*\{/ &&					# do {...
+			    $dstat !~ /^\(\{/ &&					# ({...
 			    $ctx !~ /^.\s*#\s*define\s+TRACE_(?:SYSTEM|INCLUDE_FILE|INCLUDE_PATH)\b/)
 			{
 				$ctx =~ s/\n*$//;