bnx2x: Fix intermittent long KR2 link up time

When a KR2 device is connected to a KR link-partner, sometimes it requires
disabling KR2 for the link to come up. To get a KR2 link up later, in case no
base pages are seen, the KR2 is restored. The problem was that some link
partners cleared their advertised BP/NP after around two seconds, causing the
driver to disable/enable KR2 link all the time.
The fix was to wait at least 5 seconds before checking KR2 recovery.

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>