side-switch: add service to run side-switch function

The side switch check should occur on any host firmware boot so put in
the obmc-host-startmin@.target. Ensure this service does not run when
the BMC is reset while the host is at runtime. Do not want to ever cause
a power down of a running host.

Tested:
- Booted system with running firmware at priority 0 and verified a quick
  return and successful boot.
- Booted system with running firmware at priority 1 and verified system
  was powered off, bmc was rebooted to other image, and system auto
  powered on up to operating system.

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: I5553ab6fb5ebd58734d1169663ea25ede7f37dd3
2 files changed