Bluetooth: Improve error message printing

Instead of printing:
"[ 7763.082007] Bluetooth: 2"
print something like:
"[ 7763.082007] Bluetooth: Trailing bytes: 2 in sframe"

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>