ethernet: fix dmac check avx2 loop condition

ethernet: fix dmac check avx2 loop condition

In eth_input_process_frame(), a loop which checks the destination
MAC address of received packets had a different condition for avx2
than it did for the non-avx2 version of the loop. It could result
in one unnecessary execution of the loop body after all packets
had been processed.

Type: fix
Fixes: 8d6f34e2b1cbfde5702e88686631527d5e1e10a0

Change-Id: Ib673f45917a0dea461987fdc8f0ca318b749fb1a
Signed-off-by: Matthew Smith <mgsmith@netgate.com>