regs: Add/install monitor disable service

Create a service file to call a method within the phosphor-regulators
binary to disable monitoring of the regulators. Add this service file to
be installed within the systemd services
directory(`/lib/systemd/system/`).

Tested:
    Disable of monitoring is called the earliest after a request to
poweroff

Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
Change-Id: Idd8ad73c807faddc90a7d86fd09da0508d5461dd
diff --git a/services/phosphor-regulators-monitor-disable.service b/services/phosphor-regulators-monitor-disable.service
new file mode 100644
index 0000000..d69d50e
--- /dev/null
+++ b/services/phosphor-regulators-monitor-disable.service
@@ -0,0 +1,12 @@
+[Unit]
+Description=Phosphor Power Regulators Disable Monitoring
+Wants=obmc-host-stop-pre@0.target
+Before=obmc-host-stop-pre@0.target
+Conflicts=phosphor-regulators-monitor-enable.service
+
+[Service]
+RemainAfterExit=yes
+ExecStart=/usr/bin/regsctl monitor --disable
+
+[Install]
+WantedBy=obmc-host-stop@0.target