qed*: Fix link indication race

Driver changes the link properties via communication with
the management firmware, and re-reads the resulting link status
when it receives an indication that the link has changed.
However, there are certain scenarios where such indications
might be missing, and so driver also re-reads the current link
results without attention in several places. Specifically, it
does so during load and when resetting the link.

This creates a race where driver might reflect incorrect
link status - e.g., when explicit reading of the link status is
switched by attention with the changed configuration.

Correct this flow by a lock syncronizing the handling of the
link indications [both explicit requests and attention].

Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>