ALSA: control: remove entry limitation for list operation

In current implementation of ALSA control core, list operation has
a limitation to handle 16384 entries at once. This seems due to
allocation in kernel space to copy data from user space.

With a commit 53e7bf45 ("ALSA: control: Simplify snd_ctl_elem_list()
implementation"), for the operation, ALSA control core copies data
into user space directly. No need to care of kernel spaces anymore.

This commit purges the limitation.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>