dt-bindings: interrupt-controller: Document Broadcom STB HIF L2

Add documentation for the brcm,hif-spi-l2-intc compatible string to the
brcm,l2-intc.txt binding document.

Signed-off-by: Florian Fainelli <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: ffainelli

Documentation/devicetree/bindings/interrupt-controller/brcm,l2-intc.txt

@@ -2,7 +2,9 @@ Broadcom Generic Level 2 Interrupt Controller
 
 Required properties:
 
-- compatible: should be "brcm,l2-intc" for latched interrupt controllers
+- compatible: should be one of:
+	      "brcm,hif-spi-l2-intc" or
+	      "brcm,l2-intc" for latched interrupt controllers
               should be "brcm,bcm7271-l2-intc" for level interrupt controllers
 - reg: specifies the base physical address and size of the registers
 - interrupt-controller: identifies the node as an interrupt controller