msm: clock: Move XO voting to RPM clock driver

Replace the XO voting code in the clock drivers with RPM clocks
for the respective XOs. This is more in line with how the clocks
are implemented on the RPM side (in the clock driver) and also
allows us finer grained control over when CXO/PXO is enabled in
the active set (see 9615).

Change-Id: I84c3ca17ef3b3131b1cf45331349a1800bc35c54
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>