checkpatch: correct check for kernel parameters doc

Adding a new kernel parameter with documentation makes checkpatch complain

  __setup appears un-documented -- check Documentation/admin-guide/kernel-parameters.rst

The list of kernel parameters has moved to a separate txt file, but
checkpatch has not been updated for this.

Make checkpatch.pl look for the documentation for new kernel parameters
in kernel-parameters.txt instead of kernel-parameters.rst.

Fixes: e52347bd ("Documentation/admin-guide: split the kernel parameter list to a separate file")
Signed-off-by: Tim Froidcoeur <tim.froidcoeur@tessares.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Joe Perches <joe@perches.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -2407,7 +2407,7 @@ sub process {
 
 		if ($rawline=~/^\+\+\+\s+(\S+)/) {
 			$setup_docs = 0;
-			if ($1 =~ m@Documentation/admin-guide/kernel-parameters.rst$@) {
+			if ($1 =~ m@Documentation/admin-guide/kernel-parameters.txt$@) {
 				$setup_docs = 1;
 			}
 			#next;
@@ -6388,7 +6388,7 @@ sub process {
 
 			if (!grep(/$name/, @setup_docs)) {
 				CHK("UNDOCUMENTED_SETUP",
-				    "__setup appears un-documented -- check Documentation/admin-guide/kernel-parameters.rst\n" . $herecurr);
+				    "__setup appears un-documented -- check Documentation/admin-guide/kernel-parameters.txt\n" . $herecurr);
 			}
 		}