[ALSA] continue on IS_ERR from platform device registration

I previously only concerned myself with sound/isa. When I now checked
for more platform_device_register_simple() usages in ALSA I found a
couple more drivers that needed the same patches as already submitted
for all the ISA drivers.
This first one is the continue-on-iserr patch for sound/drivers. This
gets them all.

Signed-off-by: Rene Herman <rene.herman@keyaccess.nl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>