BACKPORT: scsi: ufs: core: Fix task management completion timeout race

__ufshcd_issue_tm_cmd() clears req->end_io_data after timing out, which
races with the completion function ufshcd_tmc_handler() which expects
req->end_io_data to have a value.

Note __ufshcd_issue_tm_cmd() and ufshcd_tmc_handler() are already
synchronized using hba->tmf_rqs and hba->outstanding_tasks under the
host_lock spinlock.

It is also not necessary (nor typical) to clear req->end_io_data because
the block layer does it before allocating out requests e.g. via
blk_get_request().

So fix by not clearing it.

Bug: 210094292
(cherry picked from commit 886fe291)
Change-Id: I2c6f8b81f2aed10a85c167aa97dcbe9496677de5
[Stanley: Resolved minor conflict in drivers/scsi/ufshcd.c]
Link: https://lore.kernel.org/r/20211108064815.569494-2-adrian.hunter@intel.com


Fixes: f5ef336f ("scsi: ufs: core: Fix task management completion")
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>