dt-bindings: timer: nuvoton,npcm7xx: Add wpcm450-timer

Add a compatible string for WPCM450, which has essentially the same
timer controller.
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210320181610.680870-6-j.neuschaefer@gmx.net

Documentation/devicetree/bindings/timer/nuvoton,npcm7xx-timer.txt

@@ -4,7 +4,8 @@ Nuvoton NPCM7xx have three timer modules, each timer module provides five 24-bit
 timer counters.
 
 Required properties:
-- compatible      : "nuvoton,npcm750-timer" for Poleg NPCM750.
+- compatible      : "nuvoton,npcm750-timer" for Poleg NPCM750, or
+                    "nuvoton,wpcm450-timer" for Hermon WPCM450.
 - reg             : Offset and length of the register set for the device.
 - interrupts      : Contain the timer interrupt of timer 0.
 - clocks          : phandle of timer reference clock (usually a 25 MHz clock).