i40e: Change the notion of src and dst for FD_SB in ethtool

In XL710 devices we program FD filter's fields from Tx perspective of the flow.
However the user interface exposed in ethtool should be compliant with the
previous generation of drivers where a filter src and dst field are from
the RX perspective. This patch changes the ethtool interface in this regard
to match the other drivers.

Change-ID: Iec6ccddd87357c4fb53ccf33aa0fae699faf70cf
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>