msm: mdss: Mode switch panel clk ctrl uses dsi clk handle

As of commit be2f6d25 ("msm: mdss: dsi: create dsi clock manager")
dsi clock management was split into two clients: mdp and dsi. Cmd mode
interface uses the mdp client handle and everything else using dsi
client handle. When transitioning from one dsi mode to another, clocks
need to be rebalanced. In order to rebalance properly, mode switch is
required to vote using the dsi client handle. Modified input argument to
MDSS_EVENT_PANEL_CLK_CTRL to allow for client handle selection.

Change-Id: Id54d72de603e2115451a49fed961d01f4440c517
Signed-off-by: Terence Hampson <thampson@codeaurora.org>