dt-bindings: mtd: Add Nand Flash Controller support for Intel LGM SoC

Add YAML file for dt-bindings to support NAND Flash Controller
on Intel's Lightning Mountain SoC.

Signed-off-by: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@linux.intel.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20201110012333.18647-2-vadivel.muruganx.ramuthevar@linux.intel.com