mfd: sprd-sc27xx: Fix wakeup source leaks on device unbind

Device can be unbound, so driver must also release memory for the wakeup
source.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250406-mfd-device-wakekup-leak-v1-8-318e14bdba0a@linaro.org


Signed-off-by: Lee Jones <lee@kernel.org>