Change low power stats format to make it easier for parsing

New format: PlatformIdleStat state_1 name=XO_shutdown time=0 count=0
voter_1 name=APSS time=48264099 count=484 voter_2 name=MPSS
time=48573849 count=39857 voter_3 name=LPASS time=49584723 count=2082 
state_2 name=VMIN time=47171000 count=38222

Old format: PlatformIdleStat XO_shutdown_time=0 XO_shutdown_count=0 
APSS_time=9467486 APSS_count=583 MPSS_time=10835070 MPSS_count=9131
LPASS_time=10624719 LPASS_count=595 VMIN_time=9231000 VMIN_count=7878

In the old format it was hard to differentiate between the various
low power states and the voters for each state.

Bug:26564574

Change-Id: I3930aaf1c8c6e17066ef043552096ba61373f9f4