clk: qcom: dispcc: Removal vdd voting for xo clock

As the XO clock is marked critical the parent cannot keep a vdd vote,
thus remove the voltage voting. Also update the critical xo clocks
parents to active only source to avoid XO shutdown.

Change-Id: I6caca4b64528f7c577914509f31f5e6c3bb7ba3b
Signed-off-by: Taniya Das <tdas@codeaurora.org>