mtd: rawnand: ingenic: Make jz4725b_ooblayout_ops static

Fix sparse warning:

drivers/mtd/nand/raw/ingenic/ingenic_nand.c:140:32: warning:
 symbol 'jz4725b_ooblayout_ops' was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

drivers/mtd/nand/raw/ingenic/ingenic_nand.c

@@ -137,7 +137,7 @@ static int jz4725b_ooblayout_free(struct mtd_info *mtd, int section,
 	return 0;
 }
 
-const struct mtd_ooblayout_ops jz4725b_ooblayout_ops = {
+static const struct mtd_ooblayout_ops jz4725b_ooblayout_ops = {
 	.ecc = jz4725b_ooblayout_ecc,
 	.free = jz4725b_ooblayout_free,
 };