consitify do_mount() arguments

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

security/tomoyo/common.h

@@ -970,7 +970,7 @@ int tomoyo_init_request_info(struct tomoyo_request_info *r,
 			     const u8 index);
 int tomoyo_mkdev_perm(const u8 operation, struct path *path,
 		      const unsigned int mode, unsigned int dev);
-int tomoyo_mount_permission(char *dev_name, struct path *path,
+int tomoyo_mount_permission(const char *dev_name, struct path *path,
 			    const char *type, unsigned long flags,
 			    void *data_page);
 int tomoyo_open_control(const u8 type, struct file *file);