vmxnet3: Drop net_vmxnet3_info.can_receive

Commit 6e99c631 ("net/socket: Drop net_socket_can_send") changed the
semantics around .can_receive for sockets to now require the device to
flush queued pkts when transitioning to a .can_receive=true state. But
it's OK to drop incoming packets when the link is not active.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>