Bluetooth: Fix PSM value for L2CAP connectionless data packets

The put_unaligned() for setting the PSM is missing the (__le16 *)
cast. Without this, the PSM information transmitted over the air
are bogus.

In addition, print the used PSM value in the debug message so this
becomes easier to debug in the future.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>