staging: fsl-dpaa2/eth: add ETHERNET dependency

The new driver cannot link correctly when the netdevice infrastructure
is disabled:

ERROR: "netdev_info" [drivers/staging/fsl-dpaa2/ethernet/fsl-dpaa2-eth.ko] undefined!
ERROR: "skb_to_sgvec" [drivers/staging/fsl-dpaa2/ethernet/fsl-dpaa2-eth.ko] undefined!
ERROR: "napi_disable" [drivers/staging/fsl-dpaa2/ethernet/fsl-dpaa2-eth.ko] undefined!
ERROR: "napi_schedule_prep" [drivers/staging/fsl-dpaa2/ethernet/fsl-dpaa2-eth.ko] undefined!
ERROR: "__napi_schedule_irqoff" [drivers/staging/fsl-dpaa2/ethernet/fsl-dpaa2-eth.ko] undefined!
ERROR: "netif_carrier_on" [drivers/staging/fsl-dpaa2/ethernet/fsl-dpaa2-eth.ko] undefined!

This adds a dependency on NETDEVICES and ETHERNET.

Fixes: 0352d1d85201 ("staging: fsl-dpaa2/eth: Add APIs for DPNI objects")
Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/fsl-dpaa2/Kconfig

···
 config FSL_DPAA2_ETH
 	tristate "Freescale DPAA2 Ethernet"
 	depends on FSL_DPAA2 && FSL_MC_DPIO
+	depends on NETDEVICES && ETHERNET
 	---help---
 	  Ethernet driver for Freescale DPAA2 SoCs, using the
 	  Freescale MC bus driver