[PATCH] Stop snd-powermac oopsing on non-pmac hardware.

We shouldn't be assuming that ppc_md.feature_call will be present.

Signed-off-by: David Woodhouse <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

sound/ppc/pmac.c

···
  */
 static void snd_pmac_sound_feature(pmac_t *chip, int enable)
 {
-	ppc_md.feature_call(PMAC_FTR_SOUND_CHIP_ENABLE, chip->node, 0, enable);
+	if (ppc_md.feature_call)
+		ppc_md.feature_call(PMAC_FTR_SOUND_CHIP_ENABLE, chip->node, 0, enable);
 }
 
 /*