msm: clock-8084: Add ref clock lookup entry for UFS

The UFS host on 8084 provides 19.2MHz ref_clk input to UFS device.
Add a lookup entry so that UFS driver can control enable/disable
of ref clock.

Change-Id: Ia5c620429951b9209edcc123e4f35fa21f125f3b
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>