drivers/isdn/hardware/mISDN: move a dereference below a NULL test

In each case, if the NULL test is necessary, then the dereference should be
moved below the NULL test.

The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
type T;
expression E;
identifier i,fld;
statement S;
@@

- T i = E->fld;
+ T i;
  ... when != E
      when != i
  if (E == NULL) S
+ i = E->fld;
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Karsten Keil <kkeil@suse.de>

drivers/isdn/hardware/mISDN/hfcmulti.c

@@ -3615,7 +3615,7 @@ hfcm_bctrl(struct mISDNchannel *ch, u_int cmd, void *arg)
 static void
 ph_state_change(struct dchannel *dch)
 {
-	struct hfc_multi *hc = dch->hw;
+	struct hfc_multi *hc;
 	int ch, i;
 
 	if (!dch) {
@@ -3623,6 +3623,7 @@ ph_state_change(struct dchannel *dch)
 		    __func__);
 		return;
 	}
+	hc = dch->hw;
 	ch = dch->slot;
 
 	if (hc->type == 1) {