clk: Move vdd voting before set rate and parent

There could be clocks where the clock operations of set_rate_and_parent
would be defined to take care of setting rate and updating parent.
Move the vdd voting logic to ensure the vdd levels are voted prior to
updating rate and parent.

Change-Id: I57f903f95f290627d676afd567a6e6d21decf4a3
Signed-off-by: Taniya Das <tdas@codeaurora.org>