dt-bindings: qcom_nandc: IPQ6018 QPIC NAND documentation

Add the binding for the QPIC NAND used on IPQ6018 SoC.

Signed-off-by: Kathiravan T <kathirav@codeaurora.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/1602566124-13456-2-git-send-email-kathirav@codeaurora.org