fsl_pq_mdio: Fix kernel oops during OF address translation

Old P1020RDB device trees were not specifing tbipa address for
MDIO nodes, which is now causing this kernel oops:

...
eth2: TX BD ring size for Q[6]: 256
eth2: TX BD ring size for Q[7]: 256
Unable to handle kernel paging request for data at address 0x00000000
Faulting instruction address: 0xc0015504
Oops: Kernel access of bad area, sig: 11 [#1]
...
NIP [c0015504] memcpy+0x3c/0x9c
LR [c000a9f8] __of_translate_address+0xfc/0x21c
Call Trace:
[df839e00] [c000a94c] __of_translate_address+0x50/0x21c (unreliable)
[df839e50] [c01a33e8] get_gfar_tbipa+0xb0/0xe0
...

The old device trees are buggy, though having a dead ethernet is
better than a dead kernel, so fix the issue by using of_iomap().

Also, a somewhat similar issue exist in the probe() routine, though
there the oops is only a possibility. Nonetheless, fix it too.

Signed-off-by: Anton Vorontsov <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/fsl_pq_mdio.c

···
 static u32 __iomem *get_gfar_tbipa(struct fsl_pq_mdio __iomem *regs, struct device_node *np)
 {
 	struct gfar __iomem *enet_regs;
-	u32 __iomem *ioremap_tbipa;
-	u64 addr, size;
 
 	/*
 	 * This is mildly evil, but so is our hardware for doing this.
···
 		return &enet_regs->tbipa;
 	} else if (of_device_is_compatible(np, "fsl,etsec2-mdio") ||
 			of_device_is_compatible(np, "fsl,etsec2-tbi")) {
-		addr = of_translate_address(np, of_get_address(np, 1, &size, NULL));
-		ioremap_tbipa = ioremap(addr, size);
-		return ioremap_tbipa;
+		return of_iomap(np, 1);
 	} else
 		return NULL;
 }
···
 	u32 __iomem *tbipa;
 	struct mii_bus *new_bus;
 	int tbiaddr = -1;
+	const u32 *addrp;
 	u64 addr = 0, size = 0;
 	int err = 0;
 
···
 	new_bus->priv = priv;
 	fsl_pq_mdio_bus_name(new_bus->id, np);
 
+	addrp = of_get_address(np, 0, &size, NULL);
+	if (!addrp) {
+		err = -EINVAL;
+		goto err_free_bus;
+	}
+
 	/* Set the PHY base address */
-	addr = of_translate_address(np, of_get_address(np, 0, &size, NULL));
+	addr = of_translate_address(np, addrp);
+	if (addr == OF_BAD_ADDR) {
+		err = -EINVAL;
+		goto err_free_bus;
+	}
+
 	map = ioremap(addr, size);
 	if (!map) {
 		err = -ENOMEM;