ASoC: rt7*-sdw: harden jack_detect_handler

In the Linux kernel, the following vulnerability has been resolved: ASoC: rt7*-sdw: harden jack_detect_handler Realtek headset codec drivers typically check if the card is instantiated before proceeding with the jack detection. The rt700, rt711 and rt711-sdca are however missing a check on the card pointer, which can lead to NULL dereferences encountered in driver bind/unbind tests.