bnx2x: Generalize KR work-around

Previously, in case of KR link down, the driver would reset the PHY and restart
auto negotiation only when old Warpcore microcode was used (below D108).
This patch comes to generalize this by keep trying to restart KR link,
regardless of Warpcore microcode, since it was found that it solves another link
issue which source is a link-partner. As part of this change, the signal
detect is no longer a condition to apply the work-around to cover this new case.
Like before, as long as the link is down, AN will be restarted every 2 seconds.

Signed-off-by: Yaniv Rosner <yanivr@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>