msm: rpm_resources: Add ability to write specific bits to resources

Some RPM resources like RPM_CTL have configuration registers where
different bits mean different functionality. Add API to modify values
of bit values of RPM resources for active context.

Also, remove previously forced option to disallow-cpu-halt on RPM
from the driver.

Signed-off-by: Praveen Chidambaram <pchidamb@codeaurora.org>