Use two spaces for indentation instead of one to be consistent with the
rest of the file. No functional changes.

Fixes: 6b9ebf1e ("dt-bindings: display: amlogic, meson-vpu: convert to yaml")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Rob Herring <robh@kernel.org>