NAND core changes:
- Fourth batch of fixes/cleanup to the raw NAND core impacting various
  controller drivers (Sunxi, Marvell, MTK, TMIO, OMAP2).
- Checking the return code of nand_reset() and nand_readid_op().
- Removing ->legacy.erase and single_erase().
- Simplifying the locking.
- Several implicit fall through annotations.

Raw NAND controllers drivers changes:
- Fixing various possible object reference leaks (MTK, JZ4780, Atmel).
- ST:
  * Adding support for STM32 FMC2 NAND flash controller.
- Meson:
  * Adding support for Amlogic NAND flash controller.
- Denali:
  * Several cleanup patches.
- Sunxi:
  * Several cleanup patches.
- FSMC:
  * Disabling NAND on remove().
  * Resetting NAND timings on resume().

SPI-NAND drivers changes:
- Toshiba:
  * Adding support for all Toshiba products.
- Macronix:
  * Fixing ECC status read.
- Gigadevice:
  * Adding support for GD5F1GQ4UExxG.