[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 <dwmw2@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

sound/ppc/pmac.c

@@ -765,6 +765,7 @@ snd_pmac_ctrl_intr(int irq, void *devid, struct pt_regs *regs)
  */
 static void snd_pmac_sound_feature(pmac_t *chip, int enable)
 {
+	if (ppc_md.feature_call)
 		ppc_md.feature_call(PMAC_FTR_SOUND_CHIP_ENABLE, chip->node, 0, enable);
 }