Settings: Volume panel cleanup (2/2)

- Don't broadcast an intent as the frameworks part now listens for when the
preference is changed.
- Simplify the code to make it more similar to ListPreferences elsewhere.
- Move preference below 'Silent mode' and alter title to 'Volume panel style'.

Change-Id: I6144c3daed21666947b0b9cd852645ec4e3144ce

Conflicts:
	res/values/arrays.xml
	res/values/strings.xml
	src/com/android/settings/SoundSettings.java