bnxt_en: Don't print "Link speed -1 no longer supported" messages.

[ Upstream commit a8168b6cee6e9334dfebb4b9108e8d73794f6088 ]

On some dual port NICs, the 2 ports have to be configured with compatible
link speeds.  Under some conditions, a port's configured speed may no
longer be supported.  The firmware will send a message to the driver
when this happens.

Improve this logic that prints out the warning by only printing it if
we can determine the link speed that is no longer supported.  If the
speed is unknown or it is in autoneg mode, skip the warning message.

Reported-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Tested-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>