net: mvneta: do not set xdp_features for hw buffer devices

Devices with hardware buffer management do not support XDP, so do not
set xdp_features for them.

Fixes: 66c0e13a ("drivers: net: turn on XDP features")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/19b5838bb3e4515750af822edb2fa5e974d0a86b.1676196230.git.lorenzo@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>