score: remove __{put,get}_user_unknown

The point of these extern declarations is to provoke a link
error, so an architecture must not provide a symbol for them.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>

arch/score/lib/string.S

@@ -182,15 +182,3 @@ ENTRY(__clear_user)
 99:
 	.word	0b, 99b
 	.previous
-
-	.align	2
-ENTRY(__put_user_unknown)
-	.set volatile
-	ldi	r4, -EFAULT
-	br	r3
-
-	.align	2
-ENTRY(__get_user_unknown)
-	ldi	r5, 0
-	ldi	r4, -EFAULT
-	br	r3