imx: nandbcb: add support for i.MX7

Add support for updating FCB/DBBT on i.MX7:
- additional new fields in FCB structure
- Leverage hardware BCH/randomizer for writing FCB

Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
Tested-by: Max Krummenacher <max.krummenacher@toradex.com>
Reviewed-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>