checkpatch: check for OpenOCD tree, not for kernel tree

checkpatch.pl looks for Linux kernel specific paths and files
to check source tree. As openocd misses kernel files it ends
with this error message:

	Must be run from the top-level dir. of a kernel tree

This patch also renames 'kernel' -> 'openocd'
in source tree-related messages.

This is the old commit c5d8988316 ("checkpatch.pl: check for
openocd tree, not for kernel tree") re-applied.
Also remove the flag "--no-tree" from .checkpatch.conf, not
required anymore.

Change-Id: I336a66558c75494b7ae339ea63559c31f23aad84
Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/5122
Tested-by: jenkins

.checkpatch.conf

@@ -29,5 +29,4 @@
 --ignore VOLATILE
 
 # Temporarily lines, to commit checkpatch itself. To be removed!
---no-tree
 --ignore TYPO_SPELLING

tools/scripts/checkpatch.pl

@@ -97,7 +97,7 @@ Version: $V
 Options:
   -q, --quiet                quiet
   -v, --verbose              verbose mode
-  --no-tree                  run without a kernel tree
+  --no-tree                  run without an OpenOCD tree
   --no-signoff               do not check for 'Signed-off-by' line
   --patch                    treat FILE as patchfile (default)
   --emacs                    emacs compile window format
@@ -124,7 +124,7 @@ Options:
                              requires --strict for use with --file
   --min-conf-desc-length=n   set the min description length, if shorter, warn
   --tab-size=n               set the number of spaces for tab (default $tabsize)
-  --root=PATH                PATH to the kernel tree root
+  --root=PATH                PATH to the OpenOCD tree root
   --no-summary               suppress the per-file summary
   --mailback                 only produce a report in case of warnings/errors
   --summary-file             include the filename in summary
@@ -461,14 +461,16 @@ if ($tree) {
 	} else {
 		if (top_of_kernel_tree('.')) {
 			$root = '.';
-		} elsif ($0 =~ m@(.*)/scripts/[^/]*$@ &&
+		# OpenOCD specific: Begin: replace s"/scripts/"/tools/scripts/"
+		} elsif ($0 =~ m@(.*)/tools/scripts/[^/]*$@ &&
 						top_of_kernel_tree($1)) {
 			$root = $1;
 		}
+		# OpenOCD specific: End
 	}
 
 	if (!defined $root) {
-		print "Must be run from the top-level dir. of a kernel tree\n";
+		print "Must be run from the top-level dir. of an OpenOCD tree\n";
 		exit(2);
 	}
 }
@@ -1365,11 +1367,19 @@ exit($exit);
 sub top_of_kernel_tree {
 	my ($root) = @_;
 
+	if (!$OpenOCD) {
 	my @tree_check = (
 		"COPYING", "CREDITS", "Kbuild", "MAINTAINERS", "Makefile",
 		"README", "Documentation", "arch", "include", "drivers",
 		"fs", "init", "ipc", "kernel", "lib", "scripts",
 	);
+	} # !$OpenOCD
+	# OpenOCD specific: Begin
+	my @tree_check = (
+		"AUTHORS", "BUGS", "COPYING", "HACKING", "Makefile.am",
+		"README", "contrib", "doc", "src", "tcl", "testing", "tools",
+	);
+	# OpenOCD specific: End
 
 	foreach my $check (@tree_check) {
 		if (! -e $root . '/' . $check) {