dt-bindings: serial: Update Qualcomm geni based QUP UART bindings

Similar to I2C controller, move geni based QUP UART controller binding
out from parent schema to an individual binding and let parent refer to
child schema later on. UART binding also stand incomplete right now
similar to I2C, complete it along this process.

Signed-off-by: Kuldeep Singh <singh.kuldeep87k@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220404182938.29492-4-singh.kuldeep87k@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>