dt-bindings: meson-uart: DT fix s/clocks-names/clock-names/

- interrupts : identifier to the device interrupt

- clocks : a list of phandle + clock-specifier pairs, one for each

	   entry in clock names.

- clocks-names :

- clock-names :

   * "xtal" for external xtal clock identifier

   * "pclk" for the bus core clock, either the clk81 clock or the gate clock

   * "baud" for the source of the baudrate generator, can be either the xtal