rpm-stats: Export rpm-stats info to sysfs interface

Export rpm-stats to userspace using sysfs. This data is needed
in the userspace to process xo shutdown information for power
monitoring.

Change-Id: I90b77c7587f892bdb00455b06d2604c386c10393
Signed-off-by: Karthik Parsha <kparsha@codeaurora.org>