soc: versatile: realview: fix memory leak during device remove

If device is unbound, the memory allocated for soc_dev_attr should be
freed to prevent leaks.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/20240825-soc-dev-fixes-v1-2-ff4b35abed83@linaro.org


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>