kasan: No KASAN's memmove check if archs don't have it.

If archs don't have memmove then the C implementation from lib/string.c is used,
and then it's instrumented by compiler. So there is no need to add KASAN's
memmove to manual checks.
Signed-off-by: Nick Hu <nickhu@andestech.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

mm/kasan/common.c

@@ -110,6 +110,7 @@ void *memset(void *addr, int c, size_t len)
 	return __memset(addr, c, len);
 }
 
+#ifdef __HAVE_ARCH_MEMMOVE
 #undef memmove
 void *memmove(void *dest, const void *src, size_t len)
 {
@@ -118,6 +119,7 @@ void *memmove(void *dest, const void *src, size_t len)
 
 	return __memmove(dest, src, len);
 }
+#endif
 
 #undef memcpy
 void *memcpy(void *dest, const void *src, size_t len)