init: add rmt_storage2 service

* This is a shitty hack to get around selinux policies on
  rmt_storage.

* Normally I'd do it the proper way, but these devices are
  unlikely to ever get an official L build and therefore will
  not get a compatible rmt_storage binary. (No, mako blob
  didn't work).

* Feel free to remove the old service whenever you've updated
  your device/vendor trees.

Change-Id: I5a1009c8d7c9169b7e301ab436b5cd0a7c17af5d