package/comgt: Handle bind/unbind events

package/comgt: Handle bind/unbind events

This script was expecting only add/remove events which has not been the
case since Kernel 4.12 (which added bind/unbind). Bind events were getting
treated as remove events which would cause hotplugged 3g modems to not
work.

More info:
https://lkml.org/lkml/2018/12/23/128
https://github.com/systemd/systemd/issues/8221

Signed-off-by: Arjun AK <arjunak234@gmail.com>
Signed-off-by: maurerr <mariusd84@gmail.com>