scsi: ufs: core: Fix task management request completion timeout

ufshcd_tmc_handler() calls blk_mq_tagset_busy_iter(fn = ufshcd_compl_tm()),
but since blk_mq_tagset_busy_iter() only iterates over all reserved tags
and requests which are not in IDLE state, ufshcd_compl_tm() never gets a
chance to run. Thus, TMR always ends up with completion timeout. Fix it by
calling blk_mq_start_request() in __ufshcd_issue_tm_cmd().

Link: https://lore.kernel.org/r/1617262750-4864-2-git-send-email-cang@codeaurora.org
Fixes: 69a6c269

 ("scsi: ufs: Use blk_{get,put}_request() to allocate and free TMFs")
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>