[ALSA] opl3 - Fix compilation without sequencer support

Add proper ifdef's to the patch loading code moved from the old instr
layer so that opl3 driver can be compiled without the sequencer support.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>