clk: qcom: clk-alpha-pll: Update clk_alpha_pll_ops to bypass HW postdiv

Update clk_alpha_pll_ops to avoid post_div application in recalc_rate
ops as the present implementation applies the postdiv. Also update
clk_alpha_pll_set_rate to write the alpha value.

Change-Id: I0ae71687d80b1488475b40f45272ce6aa8de6fc0
Signed-off-by: Diptanshu Jamgade <djamgade@codeaurora.org>