ALSA: hda: cs35l56: Fix lifecycle of codec pointer

The codec should be cleared when the amp driver is unbound and when
resuming it should be tested to prevent loading firmware into the device
and ALSA in a partially configured system state.

Signed-off-by: Simon Trimmer <simont@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20240531112716.25323-1-simont@opensource.cirrus.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>