dt-bindings: pwm: Update bindings for the Meson-AXG

Update the doc to explicitly support Meson-AXG
Signed-off-by: NJian Hu <jian.hu@amlogic.com>
Signed-off-by: NYixun Lan <yixun.lan@amlogic.com>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NThierry Reding <thierry.reding@gmail.com>

Documentation/devicetree/bindings/pwm/pwm-meson.txt

@@ -5,6 +5,8 @@ Required properties:
 - compatible: Shall contain "amlogic,meson8b-pwm"
                          or "amlogic,meson-gxbb-pwm"
                          or "amlogic,meson-gxbb-ao-pwm"
+                         or "amlogic,meson-axg-ee-pwm"
+                         or "amlogic,meson-axg-ao-pwm"
 - #pwm-cells: Should be 3. See pwm.txt in this directory for a description of
   the cells format.