Add support for parsing the rate select thresholds and switching of the
RS0 and RS1 signals to the transceiver. This is complicated by various
revisions of SFF-8472 and interaction of SFF-8431, SFF-8079 and
INF-8074.
Reviewed-by: Simon Horman <simon.horman@corigine.com> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: Jakub Kicinski <kuba@kernel.org>