Fix BandMode Dialog Crash on Open due to Style

This sidesteps an error saying that the radio
BandMode activity must inherit from an AppCompat
style. Instead the window is now full-screen and
matches the theme of the RadioInfo menu.

Bug: 117571514
Test: manual - open the activity without a crash and
      verify that the new style change is effective.
Change-Id: I6e49d731e039709db43dfa6531723781e9e48640