dt-bindings: arm: fsl: Fix syntax error

Fix the following error by replacing tab indent with spaces.
"
Documentation/devicetree/bindings/arm/fsl.yaml:930:46: [error] syntax error: found character '\t' that cannot start any token (syntax)
"

Fixes: d2bf7abf ("dt-bindings: arm: fsl: Add Emtop SoM & Baseboard")
Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Documentation/devicetree/bindings/arm/fsl.yaml

@@ -927,8 +927,8 @@ properties:
 
       - description: Emtop i.MX8MM based Boards
         items:
-          - const: ees,imx8mm-emtop-baseboard			# i.MX8MM Emtop SoM on i.MX8M Mini Baseboard V1
-          - const: ees,imx8mm-emtop-som			# i.MX8MM Emtop SOM-IMX8MMLPD4 module
+          - const: ees,imx8mm-emtop-baseboard      # i.MX8MM Emtop SoM on i.MX8M Mini Baseboard V1
+          - const: ees,imx8mm-emtop-som            # i.MX8MM Emtop SOM-IMX8MMLPD4 module
           - const: fsl,imx8mm
 
       - description: Engicam i.Core MX8M Mini SoM based boards