msm: rpm_rbcpr_stats_v2: Support to query RBCPR stats

Support to query stats pertaining to RBCPR (Rapid Bridge Core Power
Reduction) from RPM data memory. The RBCPR module on the RPM modifies
voltage levels for certain chip level voltage rails based on feedback from
different sensors. This change allows querying for the RBCPR stats
maintained on RPM's data memory.

Change-Id: Ia3bdf1ef39c4064b2c3d7406b219e95c18ced21d
Signed-off-by: Girish Mahadevan <girishm@codeaurora.org>