tg3: Restrict large prod ring cap devices

Future devices may or may not be capable of supporting larger rx
producer rings.  This patch changes the code so that this flag is set on
an ASIC rev to ASIC rev basis.  Also, this patch changes a place where
the LRG_PROD_RING_CAP flag was not controlling how the rx standard
producer ring size was set.

Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>