arm64: dts: rockchip: drop redundant disable-gpios in Lubancat 2

There is no "disable-gpios" property in the PCI bindings or Linux
driver, so assume this was copied from downstream.  This property looks
like some real hardware, just described wrongly.  Rockchip PCIe
controller (DesignWare based) does not define any other GPIO-s property,
except reset-gpios which is already there, so not sure what would be the
real property for this GPIO.

This fixes dtbs_check warning:

  rk3568-lubancat-2.dtb: pcie@fe260000: Unevaluated properties are not allowed ('disable-gpios' was unexpected)

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240407102854.38672-4-krzysztof.kozlowski@linaro.org
Signed-off-by: Heiko Stuebner <heiko@sntech.de>