block: Fix the type of 'sts' in bsg_queue_rq()

This patch fixes the following sparse warnings:

block/bsg-lib.c:269:19: warning: incorrect type in initializer (different base types)
block/bsg-lib.c:269:19:    expected int sts
block/bsg-lib.c:269:19:    got restricted blk_status_t [usertype]
block/bsg-lib.c:286:16: warning: incorrect type in return expression (different base types)
block/bsg-lib.c:286:16:    expected restricted blk_status_t
block/bsg-lib.c:286:16:    got int [assigned] sts

Cc: Martin Wilck <mwilck@suse.com>
Fixes: d46fe2cb ("block: drop device references in bsg_queue_rq()")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>