EngineController: fall-back to Phonon's equalizer band names on parse error

We used to parse equalizer band names as returned by phonon, but it
seems that at least some phonon backeds now just return "band0",
"band1" etc. Fallback to phonon names to expose the bug and let
Phonomials do something with it.

Note that there's one unrelated bug: Amarok doesn't recognise phonon
equalizer doesn't support pre-amplifier and misaligns labels by one.

CCBUG: 280318