block: bfq: Remove an unused function definition

This patch is the result of the analysis of a sparse report.

Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20220617204433.102022-1-bvanassche@acm.org

block/bfq-cgroup.c

@@ -1471,8 +1471,6 @@ struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
 	return bfqq->bfqd->root_group;
 }
 
-void bfqg_and_blkg_get(struct bfq_group *bfqg) {}
-
 void bfqg_and_blkg_put(struct bfq_group *bfqg) {}
 
 struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)