scsi: ufs: Don't update urgent bkops level when toggle auto bkops

Urgent bkops level is used to compare against actual bkops status read
from UFS device. Urgent bkops level is set during initialization and might
be updated in exception event handler during runtime, but it should not be
updated to the actual bkops status every time when auto bkops is toggled.
Otherwise, if urgent bkops level is updated to 0, auto bkops shall always
be kept enabled.

Change-Id: I27e1ce00acc171c7c111dc3073ecdb23bd509851
Signed-off-by: Can Guo <cang@codeaurora.org>