mtd: ndfc: silence an underflow static checker warning

[Dan Carpenter]

"cs" is an index into the ndfc_ctrl[].  There is a sanity check which
does:

	if (cs >= NDFC_MAX_CS) {

It doesn't check for underflows and that upsets my static checker.

Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>

diff --git a/drivers/mtd/nand/ndfc.c b/drivers/mtd/nand/ndfc.c
index 8e148f1..cd78b81 100644
--- a/drivers/mtd/nand/ndfc.c
+++ b/drivers/mtd/nand/ndfc.c
@@ -201,8 +201,9 @@ static int ndfc_probe(struct platform_device *ofdev)
 {
 	struct ndfc_controller *ndfc;
 	const __be32 *reg;
+	unsigned int cs;
 	u32 ccr;
-	int err, len, cs;
+	int err, len;
 
 	/* Read the reg property to get the chip select */
 	reg = of_get_property(ofdev->dev.of_node, "reg", &len);