net/i40e: fix setting MAC address of VF

New MAC address is copied to dev->data->mac_addrs[0] before calling
setting MAC address ops. So it will fail when deleting
dev->data->mac_addrs[0]. Deleting hw->mac.addr will fix the issue.

Fixes: 943c2d899a0c ("net/i40e: set VF MAC from VF")
Cc: stable@dpdk.org
Signed-off-by: Beilei Xing <beilei.xing@intel.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>