host-gpio-monitor: Use systemd template

The systemd target gbmc-bare-metal-active.target is being changed to a
template, in order to support multi-host systems. The commit updates the
host-gpio-monitor functionality accordingly. The host number now gets
passed in as an argument.

Tested:
Set the bare metal flag /var/google/config-package/enable-bm.flag on the
BMC. Started host-gpio-monitor@0.service, which then started
gbmc-bare-metal-active@0.target. Then rebooted the host, at which point,
the host-gpio-monitor@0.service disabled
gbmc-bare-metal-active@0.target.

Change-Id: I02a0b11996aa2ee168e682fbf61f3f1a8cf01771
Signed-off-by: John Wedig <johnwedig@google.com>
3 files changed