blk_mq: remove repeated includes

Remove a repeated "#include<linux/sched/sysctl.h>".

Signed-off-by: Guo Zhengkui <guozhengkui@vivo.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20211123063340.25882-1-guozhengkui@vivo.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>