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