selftests: drv-net: add configs for zerocopy Rx

Looks like neither IO_URING nor UDMABUF are enabled even tho
iou-zcrx.py and devmem.py (respectively) need those.
IO_URING gets enabled by default but UDMABUF is missing.

Reviewed-by: Joe Damato <joe@dama.to>
Reviewed-by: Mina Almasry <almasrymina@google.com>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250811231334.561137-2-kuba@kernel.org


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