net: stmmac: Enable CRC clipping bit

When the bit is set the last four bytes of the ethernet
packet type is stripped and dropped before forwarding.

Change-Id: I740a513c90a85e3a390984602fd12539e567fc11
Acked-by: Abhishek Chauhan <abchauha@qti.qualcomm.com>
Signed-off-by: Sunil Paidimarri <hisunil@codeaurora.org>