Make use of the newly-added generic MDIO clause 45 support and remove
redundant definitions.

Add an 'efx_' prefix to the remaining driver-specific MDIO functions
and remove arguments which are redundant with efx->mdio.prtad.
Signed-off-by: NBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The driver supports the 10Xpress PHY and XFP modules on our reference
designs SFE4001 and SFE4002 and the SMC models SMC10GPCIe-XFP and
SMC10GPCIe-10BT.
Signed-off-by: NBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>