sfc: Remove static PHY data and enumerations

New NICs have firmware managing the PHY, and we will discover the PHY
capabilities at run-time.  Replace the static data with probe() and
test_name() operations.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>