blk-mq-debugfs: Off by one in blk_mq_rq_state_name()

If rq_state == ARRAY_SIZE() then we read one element beyond the end of
the blk_mq_rq_state_name_array[] array.

Fixes: ec6dcf63c55c ("blk-mq-debugfs: Show more request state information")
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq-debugfs.c

@@ -356,7 +356,7 @@ static const char *const blk_mq_rq_state_name_array[] = {
 
 static const char *blk_mq_rq_state_name(enum mq_rq_state rq_state)
 {
-	if (WARN_ON_ONCE((unsigned int)rq_state >
+	if (WARN_ON_ONCE((unsigned int)rq_state >=
 			 ARRAY_SIZE(blk_mq_rq_state_name_array)))
 		return "(?)";
 	return blk_mq_rq_state_name_array[rq_state];