isdn: mISDN: hfcsusb: Spelling fix in comment

protocoll -> protocol
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/hardware/mISDN/hfcsusb.c

@@ -678,7 +678,7 @@ ph_state(struct dchannel *dch)
 }
 
 /*
- * disable/enable BChannel for desired protocoll
+ * disable/enable BChannel for desired protocol
  */
 static int
 hfcsusb_setup_bch(struct bchannel *bch, int protocol)