memstick: move the dereference below the NULL test

The dereference should be moved below the NULL test.

spatch with a semantic match is used to found this.
(http://coccinelle.lip6.fr/)

Signed-off-by: Wei Yongjun <[e-mail]>
Cc: Maxim Levitsky <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/memstick/host/r592.c

···
 /* Executes one TPC (data is read/written from small or large fifo) */
 static void r592_execute_tpc(struct r592_device *dev)
 {
-	bool is_write = dev->req->tpc >= MS_TPC_SET_RW_REG_ADRS;
+	bool is_write;
 	int len, error;
 	u32 status, reg;
 
···
 		return;
 	}
 
+	is_write = dev->req->tpc >= MS_TPC_SET_RW_REG_ADRS;
 	len = dev->req->long_data ?
 		dev->req->sg.length : dev->req->data_len;