on_ac_power: Fix AC adapter presence recognition
on_ac_power: Fix AC adapter presence recognition

On several machines, a file corresponding to AC adapter can be named
ADP1. The on_ac_power script  checked for AC*, which does not match
ADP1, so the script always considered the adapter to be off.

X-Gentoo-Bug: 380933
X-Gentoo-Bug-URL: http://bugs.gentoo.org/show_bug.cgi?id=380933

OpenRC/openrc,OpenRC/openrc,dwfreed/openrc,williamh/openrc,williamh/openrc,williamh/openrc,OpenRC/openrc,dwfreed/openrc,dwfreed/openrc