vmxnet3: increase maximum configurable mtu to 9190

This patch increases the maximum configurable mtu to 9190
to accommodate jumbo packets of overlay traffic.

Signed-off-by: Ronak Doshi <doshir@vmware.com>
Acked-by: Guolin Yang <gyang@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>