dt-bindings: ci-hdrc-usb2: s/gadget-itc-setting/itc-setting in example

What the code expect is "itc-setting" rather than "gadget-itc-setting",
and this is also correctly described in the optional properties.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>