These warnings become somewhat more informative when they include the
MTU value that could not be set and not just the errno.
Signed-off-by: NRasmus Villemoes <rasmus.villemoes@prevas.dk>
Link: https://lore.kernel.org/r/20201205133944.10182-1-rasmus.villemoes@prevas.dkSigned-off-by: NJakub Kicinski <kuba@kernel.org>