net/i40e: enable loopback function for X722 MAC

In FVL, there was an issue and it didn't support the loopback function
before FW 5.0. For FPK (X722) it should work.

So it needs to distinguish between the devices by checking MAC type.

Fixes: 689bba33272d ("i40e: add VEB switching support")
Fixes: bce83974ba2c ("net/i40e: set Tx loopback from PF")
Cc: stable@dpdk.org
Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>