gianfar: fix compile warning

Eliminate an uninitialized variable warning.  The code is correct, but
a pointer to the automatic variable 'addr' is passed to dma_alloc_coherent.
Since addr has never been initialized, and the compiler doesn't know
what dma_alloc_coherent will do with it, it complains.
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

drivers/net/gianfar.c

@@ -696,7 +696,7 @@ int startup_gfar(struct net_device *dev)
 {
 	struct txbd8 *txbdp;
 	struct rxbd8 *rxbdp;
-	dma_addr_t addr;
+	dma_addr_t addr = 0;
 	unsigned long vaddr;
 	int i;
 	struct gfar_private *priv = netdev_priv(dev);