dt-bindings: extcon: convert extcon-usb-gpio.txt to yaml format

Convert binding doc extcon-usb-gpio.txt to yaml format to fix below
warning:
arch/arm64/boot/dts/freescale/imx8mp-msc-sm2s-ep1.dtb: /extcon-usb0:
    failed to match any schema with compatible: ['linux,extcon-usb-gpio']

Additional change:
- rename id-gpio to id-gpios
- rename vbus-gpio to vbus-gpios

Link: https://lore.kernel.org/lkml/20240812201754.3830198-1-Frank.Li@nxp.com/


Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>