This change adds support to PowerStatsHAL on sunfish devices for reading
NFC power state stats for inclusion with other subsystem power state stats.
The data is already present in sysfs; this CL (in combination with the
associated selinux change) simply adds reading of that data.
Bug: 217388683
Test: lshal debug android.hardware.power.stats@1.0::IPowerStats/default
Test: cat /sys/class/misc/st21nfc/device/power_stats
Change-Id: Ie0dc14880ba57722c2c43c8cf40783bcd3ff14b9
74ec016952