EMU10K1/EMU10K2 driver
This patch provides better sync between multiple voices by separating
the trigger_voice function into prepare_voice which sets up the volume
and filter parameters and trigger_voice which sets pitch target, current
and initial pitch and enables the voice interrupt.  For standard PCM
this should not make much of a difference but will be important for
minimizing phase error between voices for multichannel PCM.

This behavior was derived from the opensource.creative.com driver.
Signed-off-by: Lee Revell <rlrevell@joe-job.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>