Implement method to check if device is a real phone or a real tablet

This fixes rotation modes on phones, as getResources() was returning
tablet resources, because com.android.settings layout was 720.
This method cannot be used to test if systemui is on tablet mode (as for
disabling systemui tablet specific features that can be unlocked with hybrid),
it must just be used when checking if phone is a real tablet/phone.

Conflicts:
	src/com/android/settings/DisplaySettings.java