net/net_rx_pkt: Use iovec for net_rx_pkt_set_protocols()

igb does not properly ensure the buffer passed to
net_rx_pkt_set_protocols() is contiguous for the entire L2/L3/L4 header.
Allow it to pass scattered data to net_rx_pkt_set_protocols().

Fixes: 3a977dee ("Intrdocue igb device emulation")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Sriram Yagnaraman <sriram.yagnaraman@est.tech>
Signed-off-by: Jason Wang <jasowang@redhat.com>