bkops level should be rechecked upon receiving an exception.  Currently the
level is being cached and never updated.

Update bkops each time the level is checked.  Also do not use the cached
bkops level value if it is disabled and then enabled.

Fixes: afdfff59 (scsi: ufs: handle non spec compliant bkops behaviour by device)
Link: https://lore.kernel.org/r/1574751214-8321-2-git-send-email-cang@qti.qualcomm.comReviewed-by: NBean Huo <beanhuo@micron.com>
Reviewed-by: NAlim Akhtar <alim.akhtar@samsung.com>
Tested-by: NAlim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: NAsutosh Das <asutoshd@codeaurora.org>
Signed-off-by: NCan Guo <cang@codeaurora.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>