dt-bindings: cpu: Fix JSON schema

Commit fd73403a ("dt-bindings: arm: Add SMP enable-method for
Milbeaut") added support for a new cpu enable-method, but did so using
tabulations to ident. This is however invalid in the syntax, and resulted
in a failure when trying to use that schemas for validation.

Use spaces instead of tabs to indent to fix this.

Fixes: fd73403a ("dt-bindings: arm: Add SMP enable-method for Milbeaut")
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Sugaya Taichi <sugaya.taichi@socionext.com>
Signed-off-by: Olof Johansson <olof@lixom.net>

Documentation/devicetree/bindings/arm/cpus.yaml

@@ -228,7 +228,7 @@ patternProperties:
                 - renesas,r9a06g032-smp
                 - rockchip,rk3036-smp
                 - rockchip,rk3066-smp
-		- socionext,milbeaut-m10v-smp
+                - socionext,milbeaut-m10v-smp
                 - ste,dbx500-smp
 
       cpu-release-addr: