[ALSA] opl3sa2 driver - added support for PnP BIOS devices

OPL3SA2 driver
The driver has been extended to support also PnP BIOS devices.
The detection path is:

1) detect PnP BIOS devices
2) detect ISA PnP devices

Signed-off-by: Jaroslav Kysela <perex@suse.cz>