bnx2: Increase max rx ring size from 1K to 2K

A number of customers are reporting packet loss under certain workloads
(e.g. heavy bursts of small packets) with flow control disabled.  A larger
rx ring helps to prevent these losses.

No change in default rx ring size and memory consumption.

Signed-off-by: Andy Gospodarek <andy@greyhouse.net>
Acked-by: John Feeney <jfeeney@redhat.com>
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>