dt: bindings: mtd: replace references to nand.txt with nand-controller.yaml

nand-controller.yaml replaced nand.txt however the references to it were
not updated. This change updates these references wherever it appears in
bindings documentation.

Fixes: 212e49693592 ("dt-bindings: mtd: Add YAML schemas for the generic NAND options")
Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>

mtd: nand: vf610_nfc: add device tree bindings

Signed-off-by: Bill Pringlemeir <bpringlemeir@nbsps.com>
Acked-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Stefan Agner <stefan@agner.ch>
[Brian: fixup #size-cells in example]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>