net: dec: de2104x: Increase receive ring size for Tulip

Increase Rx ring size to address issue where hardware is reaching
the receive work limit.

Before:

[  102.223342] de2104x 0000:17:00.0 eth0: rx work limit reached
[  102.245695] de2104x 0000:17:00.0 eth0: rx work limit reached
[  102.251387] de2104x 0000:17:00.0 eth0: rx work limit reached
[  102.267444] de2104x 0000:17:00.0 eth0: rx work limit reached

Signed-off-by: Lucy Yan <lucyyan@google.com>
Reviewed-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>