clang-tidy: Suppress unused private field warning

Addressed warnings reported during clang-tidy enablement by marking
unused private fields with the [[maybe_unused]] keyword in multiple
instances. This temporarily suppresses the warnings until a permanent
solution is implemented.

'''
./phosphor-regulators/src/manager.hpp:199:31: error: private field 'eventLoop' is not used [-Werror
./phosphor-regulators/src/dbus_sensor.hpp:316:23: error: private field 'bus' is not used [-Werror
'''

Tested: Verified build and unit testing.

Change-Id: I5c4424deaee8440c619f8d541ee6203c4d9d738b
Signed-off-by: Jayanth Othayoth <ojayanth@gmail.com>
diff --git a/phosphor-regulators/src/dbus_sensor.hpp b/phosphor-regulators/src/dbus_sensor.hpp
index e5898de..68982d3 100644
--- a/phosphor-regulators/src/dbus_sensor.hpp
+++ b/phosphor-regulators/src/dbus_sensor.hpp
@@ -313,7 +313,7 @@
     /**
      * D-Bus bus object.
      */
-    sdbusplus::bus_t& bus;
+    sdbusplus::bus_t& bus [[maybe_unused]];
 
     /**
      * Sensor name.
diff --git a/phosphor-regulators/src/manager.hpp b/phosphor-regulators/src/manager.hpp
index ad51d98..d52c040 100644
--- a/phosphor-regulators/src/manager.hpp
+++ b/phosphor-regulators/src/manager.hpp
@@ -196,7 +196,7 @@
     /**
      * Event to loop on
      */
-    const sdeventplus::Event& eventLoop;
+    const sdeventplus::Event& eventLoop [[maybe_unused]];
 
     /**
      * System services like error logging and the journal.