net/af_packet: support MTU change
net/af_packet: support MTU change

The underlying Linux device's MTU is changed subject to the frame size
limitations during device creation.

Signed-off-by: Chas Williams <0b157e84e60d4154692939df2093b9f4f4234416@brocade.com>
Reviewed-by: Ferruh Yigit <ba8734c3c506d2e3557bd4ac8fdaccd25bdb9aa7@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk