msm: rpm_master_stats: Add DT support for rpm master stat driver

RPM master stats driver is used to show each master stats by
reading the RPM message RAM. These stats shows the useful
information of each subsystems like "active cores", "number of
shoutdowns" and "wakeup reason" etc. Current driver do not have
the DT support and it can't be used for few targets. Hence
implementing the DT support and make the driver more generic to
support different family of chipsets.

CRs-Fixed: 517589
Change-Id: If6695939c6da5e0620f91f21a8b377be12ccb444
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>