scsi: ufs: fix locking in __ufshcd_pm_qos_hold

The function is called with locked spinlock and disabled interrupts
which is done in a wrapper function ufshcd_pm_qos_hold().
Before flushing the PM QoS voting work spinlock must be released
and interrupts must be restored. As the interrupts flags state is
saved in the wrapper function, we cannot restore the state.
Moving the locking to the internal function fixes this, which
makes the wrapper function redundant so it is deleted.

Change-Id: I167292305a25d2b8c3524dcddb51f5a7109444aa
Signed-off-by: Gilad Broner <gbroner@codeaurora.org>
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>