msm: rpm_stats: Update the base address to read rpm stats.

Update the base address of the rpm sleep stats to match the address
being used by sleep stats driver on RPM. This change is needed to
allow reading of sleep stats from RPM MSG RAM.
Decrease the size of the MSG RAM for rpm_stats to 256 bytes as it
doesn't take more than that.

Signed-off-by: Anji Jonnala <anjir@codeaurora.org>
(cherry picked from commit 660b4e4874c0ab39aae829fc03563f3017d626e2)

Change-Id: Ie6bc059133429ffe75e940aae59fee51a33264b5
Signed-off-by: Sudhir Sharma <sudsha@codeaurora.org>