checkpatch: fix path of documentation

In OpenOCD documentation is in folder "doc".
Fix search path of 'checkpatch.rst'.
This file is used to provide verbose explanation of failing
checks while using command line flag '-v'.

Change-Id: Id864369d371cbd5a24e76bf90c54ff03159051c3
Signed-off-by: Antonio Borneo <[email protected]>
Reviewed-on: https://review.openocd.org/c/openocd/+/7022
Tested-by: jenkins

Author: borneoa

tools/scripts/checkpatch.pl

@@ -78,7 +78,12 @@
 my $codespellfile = "/usr/share/codespell/dictionary.txt";
 my $user_codespellfile = "";
 my $conststructsfile = "$D/const_structs.checkpatch";
+if (!$OpenOCD) {
 my $docsfile = "$D/../Documentation/dev-tools/checkpatch.rst";
+} # !$OpenOCD
+# OpenOCD Specific: Begin
+my $docsfile = "$D/../../doc/checkpatch.rst";
+# OpenOCD Specific: End
 my $typedefsfile;
 my $color = "auto";
 my $allow_c99_comments = 1; # Can be overridden by --ignore C99_COMMENT_TOLERANCE