mainloop cleanup: moved getAttrs to hwmon namespace

Moved the code that maps a sensor type to its dbus and
hwmon components from mainloop to the hwmon namespace.

Change-Id: I7963951c9484c02d17a3eb415906859609e0efd3
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/Makefile.am b/Makefile.am
index 932e4e2..238eaef 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -24,6 +24,7 @@
 	env.cpp \
 	fan_speed.cpp \
 	fan_pwm.cpp \
-	timer.cpp
+	timer.cpp \
+	hwmon.cpp
 
 SUBDIRS = . test msl