net: ixp4xx_eth: Drop platform data support

All IXP4xx platforms are converted to device tree, the platform
data path is no longer used. Drop the code and custom include,
confine the driver in its own file.

Depend on OF and remove ifdefs around this, as we are all probing
from OF now.

Cc: David S. Miller <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20220211223238.648934-9-linus.walleij@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

include/linux/platform_data/eth_ixp4xx.h

@@ -1,21 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __PLATFORM_DATA_ETH_IXP4XX
-#define __PLATFORM_DATA_ETH_IXP4XX
-
-#include <linux/types.h>
-
-#define IXP4XX_ETH_NPEA		0x00
-#define IXP4XX_ETH_NPEB		0x10
-#define IXP4XX_ETH_NPEC		0x20
-
-/* Information about built-in Ethernet MAC interfaces */
-struct eth_plat_info {
-	u8 phy;		/* MII PHY ID, 0 - 31 */
-	u8 rxq;		/* configurable, currently 0 - 31 only */
-	u8 txreadyq;
-	u8 hwaddr[6];
-	u8 npe;		/* NPE instance used by this interface */
-	bool has_mdio;	/* If this instance has an MDIO bus */
-};
-
-#endif