dt-bindings: interrupt-controller: arm,gic-v3: Describe EPPI range support

Update the GICv3 binding to allow interrupts in the EPPI range.
Signed-off-by: Marc Zyngier <maz@kernel.org>

Documentation/devicetree/bindings/interrupt-controller/arm,gic-v3.yaml

@@ -44,12 +44,13 @@ properties:
       be at least 4.
 
       The 1st cell is the interrupt type; 0 for SPI interrupts, 1 for PPI
-      interrupts, 2 for interrupts in the Extended SPI range. Other values
-      are reserved for future use.
+      interrupts, 2 for interrupts in the Extended SPI range, 3 for the
+      Extended PPI range. Other values are reserved for future use.
 
       The 2nd cell contains the interrupt number for the interrupt type.
       SPI interrupts are in the range [0-987]. PPI interrupts are in the
       range [0-15]. Extented SPI interrupts are in the range [0-1023].
+      Extended PPI interrupts are in the range [0-127].
 
       The 3rd cell is the flags, encoded as follows:
       bits[3:0] trigger type and level flags.