dpaa_eth: Make dpaa_a050385_wa static

Fix sparse warning:

drivers/net/ethernet/freescale/dpaa/dpaa_eth.c:2065:5:
 warning: symbol 'dpaa_a050385_wa' was not declared. Should it be static?

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>