Since kernel 4.10 commit 61e84623ace3 ("net: centralize net_device
min/max MTU checking"), the range of mtu is [min_mtu, max_mtu], which
is [68, 1500] by default.
It's necessary to set a max_mtu if a mtu > 1500 is supported.
Signed-off-by: Mathias Kresin <dev@kresin.me>