dt-bindings: input: cyttsp5: document vddio-supply

dt-bindings: input: cyttsp5: document vddio-supply

The Samsung touchscreen controllers are often used with external pull-up
for the interrupt line and the I2C lines, so we might need to enable
a regulator to bring the lines into usable state. Otherwise, this might
cause spurious interrupts and reading from I2C will fail.

Document support for a "vddio-supply" that is enabled by the cyttsp5
driver so that the regulator gets enabled when needed.

Signed-off-by: Lin, Meng-Bo <linmengbo0689@protonmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Alistair Francis <alistair@alistair23.me>
Link: https://lore.kernel.org/r/20221117190507.87535-2-linmengbo0689@protonmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>