x86/string: correct memmove()'s forwarding to memcpy()

x86/string: correct memmove()'s forwarding to memcpy()

With memcpy() expanding to the compiler builtin, we may not hand it
overlapping source and destination. We strictly mean to forward to our
own implementation (a few lines up in the same source file).

Fixes: 78825e1c60fa ("x86/string: Clean up x86/string.h")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 7b93d92a35dc7c0a6e5f1f79b3c887aa3e66ddc0
master date: 2021-02-04 13:59:56 +0100