msm: clock-8974: Activate RPM clock scaling in pre_init.

The RPM has a special resource that enables clock scaling.
Vote for this resource in pre_init. Without this vote, the
RPM will return success for any clock scaling request, but
will not actually scale the clock.

Change-Id: I4bfbace0677601f613aee7eba70131fdc69add26
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>