checkpatch: don't spell-check the spelling file

Prevent checkpatch to complain for commits that add new entries
in the dictionary of misspelled words.

Remove the ignore flag TYPO_SPELLING from .checkpatch.conf, now
spelling is functional.

Change-Id: I911dedafc243e34f753d2be687977066719ff2eb
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/5123
Tested-by: jenkins

.checkpatch.conf

@@ -27,6 +27,3 @@
 --ignore SWITCH_CASE_INDENT_LEVEL
 --ignore TRACING_LOGGING
 --ignore VOLATILE
-
-# Temporarily lines, to commit checkpatch itself. To be removed!
---ignore TYPO_SPELLING

tools/scripts/checkpatch.pl

@@ -3398,6 +3398,9 @@ sub process {
 
 # Check for various typo / spelling mistakes
 		if (defined($misspellings) &&
+		    # OpenOCD specific: Begin: don't check spelling on spelling_file
+		    index($spelling_file, $realfile) + length($realfile) != length($spelling_file) &&
+		    # OpenOCD specific: End
 		    ($in_commit_log || $line =~ /^(?:\+|Subject:)/i)) {
 			while ($rawline =~ /(?:^|[^\w\-'`])($misspellings)(?:[^\w\-'`]|$)/gi) {
 				my $typo = $1;