ALSA: Include linux/io.h instead of asm/io.h

Nowadays it's recommended.  Replace all in a shot.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/ppc/pmac.c b/sound/ppc/pmac.c
index d399df4..13146d7 100644
--- a/sound/ppc/pmac.c
+++ b/sound/ppc/pmac.c
@@ -20,7 +20,7 @@
  */
 
 
-#include <asm/io.h>
+#include <linux/io.h>
 #include <asm/irq.h>
 #include <linux/init.h>
 #include <linux/delay.h>