net: dpaa2: fix dependency of config FSL_DPAA2_ETH

The NETDEVICES dependency and ETHERNET dependency hadn't
been required since dpaa2-eth was moved out of staging.
Also allowed COMPILE_TEST for dpaa2-eth.

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>