scsi: ufs: recheck bkops level if bkops is disabled

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

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

Change-Id: I78ee268aaeffa2f283a2097612dea914889243e3
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>