Revert "chroot: kill battery_monitor.service till its fixed"

This reverts commit 1b350e17

.

this is now fixed in /usr/bin/battery_monitor

root@beaglebone:~# /usr/bin/battery_monitor
TI AM335x BeagleBone Green Wireless (UNSUPPORTED breaks wl18xx exiting...)

root@beaglebone:~# /usr/bin/battery_monitor
TI AM335x BeagleBone Blue

2S Pack   Jack   #Cells   Cell
 8.22V   12.11V     4     3.03V   ^Cbattery_monitor exiting cleanly

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>