bnxt_en: Fix ethtool -a reporting.

To report flow control tx/rx settings accurately regardless of autoneg
setting, we should use link_info->req_flow_ctrl.  Before this patch,
the reported settings were only correct when autoneg was on.

Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>