AES-KW: fix in-place encryption

* cipher/cipher-aeswrap.c: move memmove call before KW IV setting

In case AES-KW in-place encryption is performed, the plaintext must be
moved to the correct destination location before the first semiblock of
the destination buffer is modified. Without the patch, the first
semiblock of the plaintext is overwritten with a6a6a6a6a6a6a6a6.

• Signed-off-by: Stephan Mueller <smueller@chronox.de>