net: l2: ieee802154: fix double address swap

As we have to provide LL addresses in big endian to userspace to be
POSIX compliant and we also do not want to reserve extra space for
such addresses, bff6a5cc introduced
a change that swaps address bytes in place in the packet before
returning the packet with LL address pointers to userspace.

Unfortunately a regression sneaked into the code base while doing
so: The byte swapping was duplicated when using 6LoWPAN compression
and the byte swapping caused decryption to fail in some cases,
see #53630. This commit fixes the problem.

Fixes: #53630

Signed-off-by: Florian Grandel <jerico.dev@gmail.com>