alsactl: Move systemd unit start-up from basic.target to sound.target

alsactl: Move systemd unit start-up from basic.target to sound.target

Ensures soundcard is ready before restoring state.

sound.target added to systemd in v18:
https://cgit.freedesktop.org/systemd/systemd/commit/?id=88dfa2938af

Simplify dependencies:
 - After=alsa-state.service is not needed because both units test for
   @daemonswitch@ with opposite outcomes.

 - After=sysinit.target is automatically added by systemd.

First proposed by Tom Yan.

Signed-off-by: Chris Mayo <aklhfex@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>