arm64: dts: qcom: ipq6018: fix NAND node name

Per schema it should be nand-controller@79b0000 instead of nand@79b0000.
Fix it to match nand-controller.yaml requirements.

Signed-off-by: Robert Marko <robimarko@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220927201218.1264506-1-robimarko@gmail.com