macb: fix warning "warning: unused variable `dev' "

Removed unused variable dev

Signed-off-by: vibi sreenivasan <vibi_sreenivasan@cms.com>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>