dt-bindings: qcom_nandc: remove chip select compatible string

Currently the compatible “qcom,nandcs” is being used for each
connected NAND device to support for multiple NAND devices in the
same bus. The same thing can be achieved by looking reg property
for each sub nodes which contains the chip select number so this
patch removes the use of “qcom,nandcs” for specifying NAND device
sub nodes.

Since there is no user for this driver currently in so
changing compatible string is safe.

Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>