msm: clock-8974: Add XO buffer voting support

The RPM provides an interface to vote for XO buffers. These
buffers can either be in software control or in pin control
mode. Provide separate RPM clocks per buffer for each mode.
Enabling a pin-control-mode clock will set the buffer in pin
control mode. Enabling a software-mode clock will enable the
buffer. Disabling works the same for both types of clocks -
the buffer is disabled.

On the RPM, the votes for pin-control versus software-enable
are separately aggregated. Software-enable has higher priority
over pin-control, and if the software-mode aggregation results
in a disable, pin-control will still be configured if there is
a pin-control vote in place.

Change-Id: Ia393c4148640e47b8987a9aa6f94d6909433a9c0
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>