msm: clock-rpm: Add clock handoff support

Similar to what's done for other clock types, hand-off the rates of RPM
clocks at boot and ensure that they remain enabled until lateinit. This
prevents the clocks from turning off before drivers that depend on them
have had a chance to assert their own votes as they initialize.

Because querying an RPM clock's status will return 0 unless the clock's
rate has previously been set, when handing off, assume these clocks are
enabled (unless the RPM call fails) so that child clocks of these RPM
clocks can still be handed off.

Change-Id: Id15201706f7a474e73f266e56fb39c01974d4653
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>