ALSA: pcm: Remove superfluous snd_info_register() calls

The calls of snd_info_register() are superfluous and should be avoided
at the procfs creation time.  They are called at the end of the whole
initialization via snd_card_register().  This patch drops such
superfluous calls, as well as cleaning up the calls of substream proc
entries with a common helper.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Signed-off-by: Takashi Iwai <tiwai@suse.de>