bnx2: Update firmware to 6.0.x.

- Improved flow control and simplified interface
- Use hardware RSS indirection table instead of the slower firmware-
  based table
- Lower latency interrupt on 5709

Signed-off-by: Michael Chan <mchan@broadcom.com>
Reviewed-by: Benjamin Li <benli@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>