dt-bindings: serial: vt8500-uart: convert to json-schema

dt-bindings: serial: vt8500-uart: convert to json-schema

Convert the VIA VT8500 and WonderMedia WM8xxx UART Controller to
newer DT schema. Created DT schema based on the .txt file which had
`compatible`, `reg`, `interrupts` and `clocks` as required properties.

Additions to the original binding
- changed the file name from vt8500-uart to via,vt8500-uart.yaml
- removed unnecessary alias from the example.

Signed-off-by: Kanak Shilledar <kanakshilledar@gmail.com>
Acked-by: Alexey Charkov <alchark@gmail.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20240612153847.52647-2-kanakshilledar@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>