drivers/mmc: 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: Pierre Ossman <drzeus@drzeus.cx>

drivers/mmc/host/tmio_mmc.c

@@ -224,14 +224,15 @@ static inline void tmio_mmc_data_irq(struct tmio_mmc_host *host)
 {
 	void __iomem *ctl = host->ctl;
 	struct mmc_data *data = host->data;
-	struct mmc_command *stop = data->stop;
+	struct mmc_command *stop;
 
 	host->data = NULL;
 
 	if (!data) {
 		pr_debug("Spurious data end IRQ\n");
 		return;
 	}
+	stop = data->stop;
 
 	/* FIXME - return correct transfer count on errors */
 	if (!data->error)