eeepc-laptop: clean up control flow in *_rfkill_notifier

Handle errors immediately in eeepc_register_rfkill_notifier and
eeepc_unregister_rfkill_notifier. This clears up the control flow for the
reader. It also removes unnecessary indentation.

Signed-off-by: Frans Klaver <fransklaver@gmail.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>