block: Remove extra part pointer NULLify in blk_rq_init()

The rq->part pointer is already NULLified in the memset() call, so - like
for other pointers in rq - don't re-NULLify.

Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20241125100258.4172774-1-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

@@ -388,7 +388,6 @@ void blk_rq_init(struct request_queue *q, struct request *rq)
 	rq->tag = BLK_MQ_NO_TAG;
 	rq->internal_tag = BLK_MQ_NO_TAG;
 	rq->start_time_ns = blk_time_get_ns();
-	rq->part = NULL;
 	blk_crypto_rq_set_defaults(rq);
 }
 EXPORT_SYMBOL(blk_rq_init);