ARM: dts: msm: move ref-clk from phy to ufs node in sdm660

This patch moves the ref-clk node from the phy node
to the ufs node.
This is done so as to turn-off the ref-clk supply when
the link is off.

Change-Id: I17139340f2208b67b9a2d99419ac6ce92c06dbe5
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>