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/isa/es18xx.c b/sound/isa/es18xx.c
index 6cc2d2b..5094b62 100644
--- a/sound/isa/es18xx.c
+++ b/sound/isa/es18xx.c
@@ -84,8 +84,8 @@
 #include <linux/isapnp.h>
 #include <linux/module.h>
 #include <linux/delay.h>
+#include <linux/io.h>
 
-#include <asm/io.h>
 #include <asm/dma.h>
 #include <sound/core.h>
 #include <sound/control.h>