mtd: nand: omap2: Fix partition creation via cmdline mtdparts

commit c9711ec5250b ("mtd: nand: omap: Clean up device tree support")
caused the parent device name to be changed from "omap2-nand.0"
to "<base address>.nand"  (e.g. 30000000.nand on omap3 platforms).
This caused mtd->name to be changed as well. This breaks partition
creation via mtdparts passed by u-boot as it uses "omap2-nand.0"
for the mtd-id.

Fix this by explicitly setting the mtd->name to "omap2-nand.<CS number>"
if it isn't already set by nand_set_flash_node(). CS number is the
NAND controller instance ID.

Fixes: c9711ec5250b ("mtd: nand: omap: Clean up device tree support")
Cc: <stable@vger.kernel.org> # 4.7+
Reported-by: Leto Enrico <enrico.leto@siemens.com>
Reported-by: Adam Ford <aford173@gmail.com>
Suggested-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/omap2.c

@@ -1856,6 +1856,15 @@ static int omap_nand_probe(struct platform_device *pdev)
 	nand_chip->ecc.priv	= NULL;
 	nand_set_flash_node(nand_chip, dev->of_node);
 
+	if (!mtd->name) {
+		mtd->name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
+					   "omap2-nand.%d", info->gpmc_cs);
+		if (!mtd->name) {
+			dev_err(&pdev->dev, "Failed to set MTD name\n");
+			return -ENOMEM;
+		}
+	}
+
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	nand_chip->IO_ADDR_R = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(nand_chip->IO_ADDR_R))