clk: qcom: Enable FSM mode for votable alpha PLLs

The votable alpha PLLs need to have the fsm mode enabled as part
of the initialization. The sequence seems to be the same as used
by clk-pll, so move the function which does this into a common
place and reuse it for the clk-alpha-pll

Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
Signed-off-by: Taniya Das <tdas@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>