checkpatch: make utf-8 test --strict

Some patches are sent in using ISO-8859 or even Windows codepage 1252.

Make checkpatch accept these by default and only emit the "Invalid UTF-8"
message when using --strict.
Signed-off-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

@@ -1609,7 +1609,7 @@ sub process {
 			my $ptr = substr($blank, 0, length($utf8_prefix)) . "^";
 			my $hereptr = "$hereline$ptr\n";
 
-			ERROR("INVALID_UTF8",
+			CHK("INVALID_UTF8",
 			    "Invalid UTF-8, patch and commit message should be encoded in UTF-8\n" . $hereptr);
 		}