net: gianfar: add missing __iomem annotation

Fix the following spare warning:
drivers/net/ethernet/freescale/gianfar.c:3521:60: warning: incorrect type in argument 1 (different address spaces)
drivers/net/ethernet/freescale/gianfar.c:3521:60: expected unsigned int [noderef] <asn:2>*addr
drivers/net/ethernet/freescale/gianfar.c:3521:60: got unsigned int [usertype] *rfbptr
drivers/net/ethernet/freescale/gianfar.c:205:16: warning: incorrect type in assignment (different address spaces)
drivers/net/ethernet/freescale/gianfar.c:205:16: expected unsigned int [usertype] *rfbptr
drivers/net/ethernet/freescale/gianfar.c:205:16: got unsigned int [noderef] <asn:2>*<noident>
drivers/net/ethernet/freescale/gianfar.c:2918:44: warning: incorrect type in argument 1 (different address spaces)
drivers/net/ethernet/freescale/gianfar.c:2918:44: expected unsigned int [noderef] <asn:2>*addr
drivers/net/ethernet/freescale/gianfar.c:2918:44: got unsigned int [usertype] *rfbptr

Signed-off-by: Kevin Hao <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/freescale/gianfar.c

···
 	struct gfar_priv_rx_q *rx_queue = NULL;
 	struct txbd8 *txbdp;
 	struct rxbd8 *rxbdp;
-	u32 *rfbptr;
+	u32 __iomem *rfbptr;
 	int i, j;
 	dma_addr_t bufaddr;
 

drivers/net/ethernet/freescale/gianfar.h

···
 	/* RX Coalescing values */
 	unsigned char rxcoalescing;
 	unsigned long rxic;
-	u32 *rfbptr;
+	u32 __iomem *rfbptr;
 };
 
 enum gfar_irqinfo_id {