sfc: basic MCDI mapping of 25/50/100G link speeds

sfc: basic MCDI mapping of 25/50/100G link speeds

BugLink: https://bugs.launchpad.net/bugs/1836635
Only handles direct speed setting, not autoneg, because the driver is
 still trying to pretend it uses the legacy ethtool API which doesn't
 have advertised/supported bits for 25/50/100G.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 702b3d51369779a1ad5b03b24911ef6b0a6caa6b)
Signed-off-by: Mauricio Faria de Oliveira <mfo@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>