dt: booting-without-of: DT fix s/#interrupt-cell/#interrupt-cells/

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Documentation/devicetree/booting-without-of.txt

@@ -1309,7 +1309,7 @@ number and level/sense information. All interrupt children in an
 OpenPIC interrupt domain use 2 cells per interrupt in their interrupts
 property.
 
-The PCI bus binding specifies a #interrupt-cell value of 1 to encode
+The PCI bus binding specifies a #interrupt-cells value of 1 to encode
 which interrupt pin (INTA,INTB,INTC,INTD) is used.
 
 2) interrupt-parent property