mtd: rawnand: ingenic: Fix ingenic_ecc dependency

If MTD_NAND_JZ4780 is y and MTD_NAND_JZ4780_BCH is m,
which select CONFIG_MTD_NAND_INGENIC_ECC to m, building fails:

drivers/mtd/nand/raw/ingenic/ingenic_nand.o: In function `ingenic_nand_remove':
ingenic_nand.c:(.text+0x177): undefined reference to `ingenic_ecc_release'
drivers/mtd/nand/raw/ingenic/ingenic_nand.o: In function `ingenic_nand_ecc_correct':
ingenic_nand.c:(.text+0x2ee): undefined reference to `ingenic_ecc_correct'

To fix that, the ingenic_nand and ingenic_ecc modules have been fused
into one single module.
- The ingenic_ecc.c code is now compiled in only if
  $(CONFIG_MTD_NAND_INGENIC_ECC) is set. This is now a boolean instead
  of tristate.
- To avoid changing the module name, the ingenic_nand.c file is moved to
  ingenic_nand_drv.c. Then the module name is still ingenic_nand.
- Since ingenic_ecc.c is no more a module, the module-specific macros
  have been dropped, and the functions are no more exported for use by
  the ingenic_nand driver.

Fixes: 15de8c6e ("mtd: rawnand: ingenic: Separate top-level and SoC specific code")
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Hulk Robot <hulkci@huawei.com>
Cc: YueHaibing <yuehaibing@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>