msm_xo: Make clock users vote on CXO_CLK instead of buffers

Users of internal MSM clocks derived from CXO should vote on the
CXO_CLK RPM resource rather than just the XO buffer resource. Voting
on CXO_CLK ensures the entire clock tree from the PMIC through to the
MSM clock controller is running, whereas voting for the buffer does
not guarantee the clock will not be gated off within the MPM.

Change-Id: I18199603bcd3ed2833409cb894536fa41711b3bb
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>