dt-bindings: remoteproc: remove unneeded ref for names

The core schema already sets a 'ref' for properties ending with 'names'.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220517070113.18023-3-krzysztof.kozlowski@linaro.org