msm: clock-8960: Allow hand-offs of already-running clocks at boot

Similar to what is done for 8x60, allow handing off of rate-
settable clocks from the bootloaders to Linux if both support
the same rate. Clocks that are not rate-settable can be handed
off just by not disabling them in reg_init.

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