bnxt_en: Enhance autoneg support.

[ Upstream commit 286ef9d64ea7435a1e323d12b44a309e15cbff0e ]

On some dual port NICs, the speed setting on one port can affect the
available speed on the other port.  Add logic to detect these changes
and adjust the advertised speed settings when necessary.

Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>