msm: mdss: dsi: Fix current leakage issue for DSI PLL 1

DSI PLL 1 leaks current after a phy s/w reset. Add support
to re-program the PLL 1 registers and correctly turn it off.

Change-Id: I9184951d0d095b188ade13faff8d834fa9bd5010
Signed-off-by: Siddhartha Agrawal <agrawals@codeaurora.org>