ice: check (DD | EOF) bits on Rx descriptor rather than (EOP | RS)

ice: check (DD | EOF) bits on Rx descriptor rather than (EOP | RS)

Tx side sets EOP and RS bits on descriptors to indicate that a
particular descriptor is the last one and needs to generate an irq when
it was sent. These bits should not be checked on completion path
regardless whether it's the Tx or the Rx. DD bit serves this purpose and
it indicates that a particular descriptor is either for Rx or was
successfully Txed. EOF is also set as loopback test does not xmit
fragmented frames.

Look at (DD | EOF) bits setting in ice_lbtest_receive_frames() instead
of EOP and RS pair.

Fixes: 0e674aeb0b77 ("ice: Add handler for ethtool selftest")
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Tested-by: George Kuruvinakunnel <george.kuruvinakunnel@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>