s390/uaccess: use __noreturn instead of __attribute__((noreturn))

Signed-off-by: Heiko Carstens <[e-mail]>

arch/s390/include/asm/uaccess.h

···
 	return n;
 }
 
-int __put_user_bad(void) __attribute__((noreturn));
-int __get_user_bad(void) __attribute__((noreturn));
-
 union oac {
 	unsigned int val;
 	struct {
···
 		} oac2;
 	};
 };
+
+int __noreturn __put_user_bad(void);
 
 #define __put_user_asm(to, from, size)					\
 ({									\
···
 	}
 	return rc;
 }
+
+int __noreturn __get_user_bad(void);
 
 #define __get_user_asm(to, from, size)					\
 ({									\