net: bgmac: remove set but not used variable 'err'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/net/ethernet/broadcom/bgmac.c: In function 'bgmac_dma_alloc':
drivers/net/ethernet/broadcom/bgmac.c:619:6: warning:
 variable 'err' set but not used [-Wunused-but-set-variable]
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bgmac.c

@@ -616,7 +616,6 @@ static int bgmac_dma_alloc(struct bgmac *bgmac)
 	static const u16 ring_base[] = { BGMAC_DMA_BASE0, BGMAC_DMA_BASE1,
 					 BGMAC_DMA_BASE2, BGMAC_DMA_BASE3, };
 	int size; /* ring size: different for Tx and Rx */
-	int err;
 	int i;
 
 	BUILD_BUG_ON(BGMAC_MAX_TX_RINGS > ARRAY_SIZE(ring_base));
@@ -666,7 +665,6 @@ static int bgmac_dma_alloc(struct bgmac *bgmac)
 		if (!ring->cpu_base) {
 			dev_err(bgmac->dev, "Allocation of RX ring 0x%X failed\n",
 				ring->mmio_base);
-			err = -ENOMEM;
 			goto err_dma_free;
 		}