openrisc: fix the fix of copy_from_user()

commit 8e4b7205 upstream.

Since commit acb2505d ("openrisc: fix copy_from_user()"),
copy_from_user() returns the number of bytes requested, not the
number of bytes not copied.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Fixes: acb2505d ("openrisc: fix copy_from_user()")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

arch/openrisc/include/asm/uaccess.h

@@ -277,7 +277,7 @@ copy_from_user(void *to, const void *from, unsigned long n)
 	unsigned long res = n;
 
 	if (likely(access_ok(VERIFY_READ, from, n)))
-		n = __copy_tofrom_user(to, from, n);
+		res = __copy_tofrom_user(to, from, n);
 	if (unlikely(res))
 		memset(to + (n - res), 0, res);
 	return res;