ALSA: pcm: Update the state properly before notification

Some state changes (e.g. snd_pcm_stop()) sets the runtime state after
calling snd_timer_notify().  This is basically racy, since the
notification may wakes up the user even before the state change.
Although the possibility is low, we should set the state before the
notifications.

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