udev: Fix sound.target dependency

The recent bug report indicated a race at device creation and the
sound.target dependencies, and the cause turned out to be the condition
of the sound.target trigger.  Currently it's set for "card*", but this
is actually the parent object; i.e. the sound.target is triggered before
the sound devices are created.

For assuring the whole sound device creations beforehand, we need to use
"controlC*" instead of "card*"; as already described in
78-sound-card.rules, this is guaranteed to be the last device, and can
be used as a synchronization point.

BugLink: https://bugzilla.suse.com/show_bug.cgi?id=1179363


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