checkpatch: support wide strings

Allow prefixing typical strings with L for wide strings and u for unicode
strings.

Link: https://lkml.kernel.org/r/20210801170733.1.I3f9784fd3c1007d08ec2e70b151d137687575495@changeid
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -501,7 +501,7 @@ sub hash_show_words {
 our $Hex	= qr{(?i)0x[0-9a-f]+$Int_type?};
 our $Int	= qr{[0-9]+$Int_type?};
 our $Octal	= qr{0[0-7]+$Int_type?};
-our $String	= qr{"[X\t]*"};
+our $String	= qr{(?:\b[Lu])?"[X\t]*"};
 our $Float_hex	= qr{(?i)0x[0-9a-f]+p-?[0-9]+[fl]?};
 our $Float_dec	= qr{(?i)(?:[0-9]+\.[0-9]*|[0-9]*\.[0-9]+)(?:e-?[0-9]+)?[fl]?};
 our $Float_int	= qr{(?i)[0-9]+e-?[0-9]+[fl]?};
@@ -6132,7 +6132,8 @@ sub process {
 		}
 
 # concatenated string without spaces between elements
-		if ($line =~ /$String[A-Za-z0-9_]/ || $line =~ /[A-Za-z0-9_]$String/) {
+		if ($line =~ /$String[A-Z_]/ ||
+		    ($line =~ /([A-Za-z0-9_]+)$String/ && $1 !~ /^[Lu]$/)) {
 			if (CHK("CONCATENATED_STRING",
 				"Concatenated strings should use spaces between elements\n" . $herecurr) &&
 			    $fix) {
@@ -6145,7 +6146,7 @@ sub process {
 		}
 
 # uncoalesced string fragments
-		if ($line =~ /$String\s*"/) {
+		if ($line =~ /$String\s*[Lu]?"/) {
 			if (WARN("STRING_FRAGMENTS",
 				 "Consecutive strings are generally better as a single string\n" . $herecurr) &&
 			    $fix) {