net: freescale: ucc_geth: Drop support for the "interface" DT property

net: freescale: ucc_geth: Drop support for the "interface" DT property

In april 2007, ucc_geth was converted to phylib with :

commit 728de4c927a3 ("ucc_geth: migrate ucc_geth to phylib").

In that commit, the device-tree property "interface", that could be used to
retrieve the PHY interface mode was deprecated.

DTS files that still used that property were converted along the way, in
the following commit, also dating from april 2007 :

commit 0fd8c47cccb1 ("[POWERPC] Replace undocumented interface properties in dts files")

17 years later, there's no users of that property left and I hope it's
safe to say we can remove support from that in the ucc_geth driver,
making the probe() function a bit simpler.

Should there be any users that have a DT that was generated when 2.6.21 was
cutting-edge, print an error message with hints on how to convert the
devicetree if the 'interface' property is found.

With that property gone, we can greatly simplify the parsing of the
phy-interface-mode from the devicetree by using of_get_phy_mode(),
allowing the removal of the open-coded parsing in the driver.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>