firewire: ohci: release channel in error path

firewire-ohci keeps book of which isochronous channels are occupied by
IR DMA contexts, so that there cannot be more than one context listening
to a certain channel.

If IR context creation failed due to an out-of-memory condition, this
bookkeeping leaked a channel.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/firewire/ohci.c

@@ -2309,6 +2309,7 @@ static struct fw_iso_context *ohci_allocate_iso_context(struct fw_card *card,
 	free_page((unsigned long)ctx->header);
  out:
 	spin_lock_irqsave(&ohci->lock, flags);
+	*channels |= 1ULL << channel;
 	*mask |= 1 << index;
 	spin_unlock_irqrestore(&ohci->lock, flags);