tg3: Return flowctrl config through ethtool

tg3: Return flowctrl config through ethtool

This patch changes the driver to return the flow control configuration
rather than the flow control status through the ETHTOOL_GPAUSEPARAM
ioctl.

(cherry picked from commit 4a2db503c57f7223d851dc7ab8cefca614e0d98a)
Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Reviewed-by: Michael Chan <mchan@broadcom.com>
Reviewed-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Joe Jin <joe.jin@oracle.com>