ALSA: pcm - Fix update of runtime->hw_ptr_interrupt

The commit 13f040f9

 made another
regression, the missing update of runtime->hw_ptr_interrupt.
Since this field is only checked in snd_pcmupdate__hw_ptr_interrupt(),
not in snd_pcm_update_hw_ptr(), it must be updated before the hw_ptr
change check.

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