mou401.h fix for kernel 2.5.50

In order to compile sound/oss/mpu401.c as it has been changed in kernel
2.5.50 this is needed:

--- linux-2.5.50/sound/oss/mpu401.h.orig        2002-11-29
13:02:01.000000000 +0100
+++ linux-2.5.50/sound/oss/mpu401.h     2002-11-29 13:01:28.000000000
+0100
@@ -7,7 +7,7 @@

 /*     From mpu401.c */
 int probe_mpu401(struct address_info *hw_config);
-void attach_mpu401(struct address_info * hw_config, struct module *owner);
+int attach_mpu401(struct address_info *hw_config, struct module *owner);
 void unload_mpu401(struct address_info *hw_info);

 int intchk_mpu401(void *dev_id);