Staging: ipack/bridges/tpci200: Clean up interrupt handler.

This also removes a possible bug in the unhandles_ints part when
slots[i] is not set.

Signed-off-by: Jens Taprogge <jens.taprogge@taprogge.org>
Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>