remove DefaultDevice's UI subclass

RecoveryUI (which is the superclass of ScreenRecoveryUI), provides a
basic CheckKey method that is useful for devices that have KEY_POWER,
KEY_VOLUMEUP, and KEY_VOLUMEDOWN.  Stop overriding it with a less
featureful method; with this no recovery UI customization is needed
for most handheld devices (phones, tablets, etc.).

Change-Id: I7d57cfaaef79afea8af4fc3dbc570afc61aeb5bc
2 files changed