x86: use the new generic strnlen_user() function

This throws away the old x86-specific functions in favor of the generic
optimized version.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/include/asm/uaccess.h

@@ -566,6 +566,9 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
 extern __must_check long
 strncpy_from_user(char *dst, const char __user *src, long count);
 
+extern __must_check long strlen_user(const char __user *str);
+extern __must_check long strnlen_user(const char __user *str, long n);
+
 /*
  * movsl can be slow when source and dest are not both 8-byte aligned
  */