[PATCH] Amifb wrong interrupt

[PATCH] Amifb wrong interrupt

Amiga frame buffer device: request the correct interrupt, so we no longer get
spurious interrupts. The old code worked only by accident.

To avoid flicker when updating the display parameters, we do not use the real
vertical blank interrupt, but instead ask the Copper to generate an interrupt
after the bitplane and sprite pointers have been set up at the beginning of
each frame.