bnxt_en: Support for "ethtool -r" command

Restart autoneg if autoneg is enabled.

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