isdn: fix random hard freeze with AVM c4 card part 2

One call was missing in the previous patch.

Signed-off-by: Karsten Keil <kkeil@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/isdn/hardware/avm/c4.c b/drivers/isdn/hardware/avm/c4.c
index 8710cf6..4bbbbe6 100644
--- a/drivers/isdn/hardware/avm/c4.c
+++ b/drivers/isdn/hardware/avm/c4.c
@@ -678,7 +678,9 @@
                 for (i=0; i < card->nr_controllers; i++) {
 			avmctrl_info *cinfo = &card->ctrlinfo[i];
 			memset(cinfo->version, 0, sizeof(cinfo->version));
+			spin_lock_irqsave(&card->lock, flags);
 			capilib_release(&cinfo->ncci_head);
+			spin_unlock_irqrestore(&card->lock, flags);
 			capi_ctr_reseted(&cinfo->capi_ctrl);
 		}
 		card->nlogcontr = 0;