firewire: cdev: fix IR multichannel event documentation

State more precisely when fw_cdev_event_iso_interrupt_mc is sent.
While the comment tried to reflect an amibuity in the OHCI
specification, there is only one method that is useful in practice,
and this also matches all the hardware implementations I've tested.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

include/linux/firewire-cdev.h

@@ -267,9 +267,8 @@ struct fw_cdev_event_iso_interrupt {
  *
  * This event is sent in multichannel contexts (context type
  * %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL) for &fw_cdev_iso_packet buffer
- * chunks that have the %FW_CDEV_ISO_INTERRUPT bit set.  Whether this happens
- * when a packet is completed and/or when a buffer chunk is completed depends
- * on the hardware implementation.
+ * chunks that have been completely filled and that have the
+ * %FW_CDEV_ISO_INTERRUPT bit set.
  *
  * The buffer is continuously filled with the following data, per packet:
  *  - the 1394 iso packet header as described at &fw_cdev_event_iso_interrupt,