net/i40e: enable maximum frame size at port level

net/i40e: enable maximum frame size at port level

Currently max frame size is set at queue level, which makes the values
of the following counters wrong when a jumbo frame is received.

The expected value:
rx_good_bytes: 0
rx_errors: 1
rx_oversize_errors: 1

The actual value:
rx_good_bytes: 1626
rx_errors: 0
rx_oversize_errors: 0

This patch enables setting max frame size at port level, and makes the
values above right.

Cc: stable@dpdk.org
Signed-off-by: Dapeng Yu <dapengx.yu@intel.com>
Tested-by: Peng Zhang <peng1x.zhang@intel.com>
Reviewed-by: Qi Zhang <qi.z.zhang@intel.com>