fiq_fsm: add missing case for fiq_fsm_tt_in_use()

Certain combinations of bitrate and endpoint activity could
result in a periodic transaction erroneously getting started
while the previous Isochronous OUT was still active.
fiq_fsm: clear hcintmsk for aborted transactions

Prevents the FIQ from erroneously handling interrupts
on a timed out channel.
fiq_fsm: enable by default