ASoC: core: Do not call link_exit() on uninitialized rtd objects

ASoC: core: Do not call link_exit() on uninitialized rtd objects

On init we have sequence:

	for_each_card_prelinks(card, i, dai_link) {
		ret = snd_soc_add_pcm_runtime(card, dai_link);

	ret = init_some_other_things(...);
	if (ret)
		goto probe_end:

	for_each_card_rtds(card, rtd) {
		ret = soc_init_pcm_runtime(card, rtd);

probe_end:

while on exit:
	for_each_card_rtds(card, rtd)
		snd_soc_link_exit(rtd);

If init_some_other_things() step fails due to error we end up with
not fully setup rtds and try to call snd_soc_link_exit on them, which
depending on contents on .link_exit handler, can end up dereferencing
NULL pointer.

Reviewed-by: Cezary Rojewski <cezary.rojewski@intel.com>
Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Link: https://lore.kernel.org/r/20230929103243.705433-2-amadeuszx.slawinski@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>