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/meson.build b/meson.build
index 9e8adb4..3c54ec4 100644
--- a/meson.build
+++ b/meson.build
@@ -50,7 +50,8 @@
     'phosphor-psu-monitor.service',
     'phosphor-regulators.service',
     'phosphor-regulators-config.service',
-    'phosphor-regulators-monitor-enable.service'
+    'phosphor-regulators-monitor-enable.service',
+    'phosphor-regulators-monitor-disable.service'
 ]
 
 foreach service : services
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