mtd: rawnand: ingenic: Rename jz4780_nand driver to ingenic_nand

The jz4780_nand driver will be modified to handle all the Ingenic
JZ47xx SoCs that the upstream Linux kernel supports (JZ4740, JZ4725B,
JZ4770, JZ4780), so it makes sense to rename it.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

drivers/mtd/nand/raw/ingenic/Makefile

 obj-$(CONFIG_MTD_NAND_JZ4740) += jz4740_nand.o
-obj-$(CONFIG_MTD_NAND_JZ4780) += jz4780_nand.o jz4780_bch.o
+obj-$(CONFIG_MTD_NAND_JZ4780) += ingenic_nand.o jz4780_bch.o