scsi: ufs: Request sense data asynchronously

Clearing a unit attention synchronously from inside the UFS error handler
may trigger the following deadlock:

 - ufshcd_err_handler() calls ufshcd_err_handling_unprepare() and the
   latter function calls ufshcd_clear_ua_wluns().

 - ufshcd_clear_ua_wluns() submits a REQUEST SENSE command and that command
   activates the SCSI error handler.

 - The SCSI error handler calls ufshcd_host_reset_and_restore().

 - ufshcd_host_reset_and_restore() executes the following code:
   ufshcd_schedule_eh_work(hba); flush_work(&hba->eh_work);

This sequence results in a deadlock (circular wait). Fix this by requesting
sense data asynchronously.

Link: https://lore.kernel.org/r/[email protected]
Cc: Adrian Hunter <[email protected]>
Cc: Stanley Chu <[email protected]>
Cc: Can Guo <[email protected]>
Cc: Asutosh Das <[email protected]>
Cc: Avri Altman <[email protected]>
Reviewed-by: Bean Huo <[email protected]>
Signed-off-by: Bart Van Assche <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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