dt-bindings: media: meson-ir: Add Meson8b and GXBB compatible strings

New bindings are needed as the register layout on the newer platforms
is slightly different compared to Meson6b.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Rob Herring <robh@kernel.org>
Tested-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>

Documentation/devicetree/bindings/media/meson-ir.txt

 * Amlogic Meson IR remote control receiver
 
 Required properties:
- - compatible	: should be "amlogic,meson6-ir"
+ - compatible	: depending on the platform this should be one of:
+		  - "amlogic,meson6-ir"
+		  - "amlogic,meson8b-ir"
+		  - "amlogic,meson-gxbb-ir"
  - reg		: physical base address and length of the device registers
  - interrupts	: a single specifier for the interrupt from the device