Revert "scsi: ufs: gate ref_clk during aggressive clk gating"

This reverts commit ca91fa16a7af ("scsi: ufs: gate ref_clk during
aggressive clk gating").

Reverting this change as its causing stability issues.

Change-Id: Ia04d33d84b5622179f7a496daee5584d4e2dde91
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
[cang@codeaurora.org: resolved trivial merge conflicts]
Signed-off-by: Can Guo <cang@codeaurora.org>