FROMLIST: scsi: ufs: atomic update for clkgating_enable

Powerhints enables/disables clkgating so frequently which leads wrong UFS
status resulting in timeout.

Bug: 158050260
Bug: 134949663
Bug: 166641672
Change-Id: Ie5002107a69e7d56a889138eec0e593de1bf6a61
Link: https://lore.kernel.org/linux-scsi/20200915204532.1672300-1-jaegeuk@kernel.org/T/#t


Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>
(cherry picked from commit b78d30de)