net: lan966x: set xdp_features flag

Set xdp_features netdevice flag if lan966x nic supports xdp mode.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Link: https://lore.kernel.org/r/01f4412f28899d97b0054c9c1a63694201301b42.1676055718.git.lorenzo@kernel.org


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