msm: pil-q6v4: Migrate to clk APIs for XO voting

Use the clock APIs instead of the msm_xo APIs to vote on CXO and
PXO. This removes one more msm specific api from this driver and
will allow us to move XO control into the rpm clock driver.

Change-Id: I57cece3891eef8a8dace1a8465dbe3737ccd0e27
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>