dt-bindings: qcom_nandc: Add SDX55 QPIC NAND documentation

Qualcomm SDX55 uses QPIC NAND controller version 2.0.0 with BAM DMA
Engine.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>