rpmh_master_stat: Add support for application processor master stats

Add support to read application processor's PDC profiling data and
display it as part of master stats.

Below command displays application processor stats along with other
master's stats.

	cat /sys/power/rpmh_stats/master_stats

APSS
        Version:0x1
        Sleep Count:0x13
        Sleep Last Entered At:0x14721eadb
        Sleep Last Exited At:0x14724a427
        Sleep Accumulated Duration:0x3a76b0

Change-Id: I2a9fa26a2418e58d185b8285e0b46549a41b4709
Signed-off-by: Maulik Shah <mkshah@codeaurora.org>