qcom: clock: Allow setting initial rates during handoff

The qti clock driver not only provides the implementation for the
various clock types, but also may behave as a client under certain
circumstances.
1) Some shared sytem clocks are configured to fixed rates after boot
2) Some clocks necessary for system operation are enabled
3) For historical reasons, the rates of some clocks are initialized
on behalf of other drivers.

Change-Id: I1d7247d3e40aa7d833a633b620ed2f6348964b91
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>