ASoC: dapm: Fix NULL pointer dereference when registering card with widgets

Commit 0bd2ac3d ("ASoC: Remove CODEC pointer from snd_soc_dapm_context")
introduced regression to snd_soc_dapm_new_controls() when registering a card
with card->dapm_widgets set. Call chain is:

    snd_soc_register_card()
    -> snd_soc_instantiate_card()
       -> snd_soc_dapm_new_controls()
          -> snd_soc_dapm_new_control()

Null pointer dereference occurs since card->dapm context doesn't have
associated component. Fix this by setting widget codec pointer
conditionally.
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/soc-dapm.c

@@ -3107,7 +3107,8 @@ snd_soc_dapm_new_control(struct snd_soc_dapm_context *dapm,
 	}
 
 	w->dapm = dapm;
-	w->codec = dapm->component->codec;
+	if (dapm->component)
+		w->codec = dapm->component->codec;
 	INIT_LIST_HEAD(&w->sources);
 	INIT_LIST_HEAD(&w->sinks);
 	INIT_LIST_HEAD(&w->list);