This should improve driver stability somewhat. Powerup problems seem to
happen when we receive 3 unrelated interrupts while waiting for the
power-on interrupt, so let's assume that the device can only buffer 3
interrupts, and when the buffer is full, it discards new ones.

When we detect a possible buffer overflow, ask the caller to retry the
operation.

Also, saw the interrupt of death a few times, so add in a warning when
this happens. Haven't seen it since handling interrupt overflows though.