bnx2x: Spread rx buffers between allocated queues

Default number of rx buffers will be divided equally
 between allocated queues. This will decrease amount of
 pre-allocated buffers on systems with multiple CPUs.
 User can override this behavior with ethtool -G.
 Minimum amount of rx buffers per queue set to 128.

Reported-by: Eric Dumazet <eric.dumazet@gmail.com>

Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>