net: macb: remove unnecessary code

Commit 653e92a9 ("net: macb: add support for padding and fcs
computation") introduced a bug fixed by commit 899ecaed ("net:
ethernet: cadence: fix socket buffer corruption problem"). Code removed
in this patch is not reachable at all so remove it.

Fixes: 653e92a9

 ("net: macb: add support for padding and fcs computation")
Cc: Tristram Ha <Tristram.Ha@microchip.com>
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>