bnxt_en: query force speeds before disabling autoneg mode.

With autoneg enabled, PHY loopback test fails. To disable autoneg,
driver needs to send a valid forced speed to FW. FW is not sending
async event for invalid speeds. To fix this, query forced speeds
and send the correct speed when disabling autoneg mode.

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