davinci_emac: pass ioctls through to phy device.

The DaVinci EMAC driver does not implement any ioctls, but still it can
pass them through to the phy device. This makes it possible for a phy
to offer PHC capabilities.

Cc: Anant Gole <anantgole@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Signed-off-by: David S. Miller <davem@conan.davemloft.net>