net: phy: Remove probe_capabilities

Deciding if to probe of PHYs using C45 is now determine by if the bus
provides the C45 read method. This makes probe_capabilities redundant
so remove it.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Acked-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>