m68k: Use BUILD_BUG for passing invalid sizes to get_user/put_user

Simplify the handling a bit by using the common helper instead of
referencing undefined symbols.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Michael Schmitz <schmitzmic@gmail.com>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Link: https://lore.kernel.org/r/20210916070405.52750-4-hch@lst.deSigned-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

arch/m68k/include/asm/uaccess.h

@@ -39,9 +39,6 @@ static inline int access_ok(const void __user *addr,
 #define	MOVES	"move"
 #endif
 
-extern int __put_user_bad(void);
-extern int __get_user_bad(void);
-
 #define __put_user_asm(res, x, ptr, bwl, reg, err)	\
 asm volatile ("\n"					\
 	"1:	"MOVES"."#bwl"	%2,%1\n"		\
@@ -105,8 +102,7 @@ asm volatile ("\n"					\
 		break;							\
 	    }								\
 	default:							\
-		__pu_err = __put_user_bad();				\
-		break;							\
+		BUILD_BUG();						\
 	}								\
 	__pu_err;							\
 })
@@ -179,8 +175,7 @@ asm volatile ("\n"					\
 		break;							\
 	}								\
 	default:							\
-		__gu_err = __get_user_bad();				\
-		break;							\
+		BUILD_BUG();						\
 	}								\
 	__gu_err;							\
 })