healthd performs privileged ioctls on the tty device
when in charger mode. Allow it.

This fixes a bug where off charging mode is forcing the device
to reboot into recovery.

Addresses the following denial:

type=1400 audit(15080631.900:4): avc:  denied  { sys_tty_config } for  pid=130 comm="healthd" capability=26  scontext=u:r:healthd:s0 tcontext=u:r:healthd:s0 tclass=capability

Bug: 13472365
Change-Id: I402987baf62ba0017e79e30e370850c32c286a6a