A VF's MTU is capped at the parent PF's MTU.  So if there's a change in the
PF's MTU, then update the VF's netdev->max_mtu.

Also remove duplicate log messages for MTU change.
Signed-off-by: NVeerasenareddy Burru <veerasenareddy.burru@cavium.com>
Signed-off-by: NRaghu Vatsavayi <raghu.vatsavayi@cavium.com>
Signed-off-by: NFelix Manlunas <felix.manlunas@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>