mtd: nand: vf610_nfc: resync with upstream Linux version

mtd: nand: vf610_nfc: resync with upstream Linux version

This resyncs the driver changes with the Linux version of the
driver. The driver received some feedback in the LKML and got
recently acceppted, the latest version can be found here:
https://lkml.org/lkml/2015/9/2/678

Notable changes are:
- On ECC error, reread OOB and count bit flips in OOB too.
  If flipped bits are below threshold, also return an empty
  OOB buffer.
- Return the amount of bit flips in vf610_nfc_read_page.
- Use endianness aware vf610_nfc_read to read ECC status.
- Do not enable IDLE IRQ (since we do not operate with an
  interrupt service routine).
- Use type safe struct for buffer variants (vf610_nfc_alt_buf).
- Renamed variables in struct vf610_nfc (column and page_sz)
  to reflect better what they really representing.

The U-Boot version currently does not support RAW NAND write
when using the HW ECC engine.

Signed-off-by: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com>
Signed-off-by: Stefan Agner <stefan@agner.ch>
Tested-by: Albert ARIBAUD (3ADEV) <albert.aribaud@3adev.fr>
Tested-by: Stefan Agner <stefan@agner.ch>
Acked-by: Scott Wood <scottwood@freescale.com>