interrupt-mapping: Fix parent interrupt specifier description

The number of cells here is not dictated by the #interrupt-cells
property of this node, but the same property in the interrupt
parent. This looks like a copy/paste mistake from child interrupt
specifier.

Signed-off-by: Stephen Boyd <[email protected]>
Signed-off-by: Rob Herring <[email protected]>

Author: bebarino

source/devicetree-basics.rst

@@ -1120,8 +1120,8 @@ Description:
    parent interrupt specifier
        The interrupt specifier in the parent domain. The number of 32-bit
        cells required to specify this component is described by the
-       *#interrupt-cells* property of this node—the nexus node containing
-       the *interrupt-map* property.
+       *#interrupt-cells* property of the node pointed to by the
+       interrupt-parent field.
 
    Lookups are performed on the interrupt mapping table by matching a
    unit-address/interrupt specifier pair against the child components in