platform/mtpd: Add systemd service file

systemd unit file that starts the mtpd daemon
BUG=chromium:583671
TEST=Checked that the mtpd daemon is up and running with
  "systemctl status mtpd". Plugged phone and I could browse
  files.
CQ-DEPEND=CL:351980
Change-Id: I2b9286ca3f6915ecf8e596f8f8fef27d850725e5
Reviewed-on: https://chromium-review.googlesource.com/351970
Commit-Ready: Sabin Floares <sabin.floares@intel.com>
Tested-by: Sabin Floares <sabin.floares@intel.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
1 file changed