Revert "[Settings] HW keys tweaks"

This reverts commit f837f80f916b8d51a8a37261c7f17190ff4fbea7.

Conflicts:
	res/xml/button_settings.xml
	src/com/android/settings/ButtonSettings.java

Change-Id: I62839e4ac19e829af5dd9a44be0e1e0e316cdfec