dpaa_eth: Fix one possible memleak in dpaa_eth_probe

When dma_coerce_mask_and_coherent() fails, the alloced netdev need to be freed.

Fixes: 060ad66f

 ("dpaa_eth: change DMA device")
Signed-off-by: Liu Jian <liujian56@huawei.com>
Acked-by: Madalin Bucur <madalin.bucur@oss.nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>