ALSA: hda - Fix possible races of accesses to connection list array

Like the previous fixes for cache hash accesses, a protection over
accesses to the widget connection list array must be provided.
Together with this action, remove snd_hda_get_conn_list() which can be
always race, and replace it with either snd_hda_get_num_conns() or
snd_hda_get_connections() calls.

Signed-off-by: Takashi Iwai <tiwai@suse.de>