Bluetooth: btusb: Add debug message for CSR controllers

The rationale of showing this is that it's potentially critical
information to diagnose and find more CSR compatibility bugs in the
future and it will save a lot of headaches.

Given that clones come from a wide array of vendors (some are actually
Barrot, some are something else) and these numbers are what let us find
differences between actual and fake ones, it will be immensely helpful
to scour the Internet looking for this pattern and building an actual
database to find correlations and improve the checks.

Cc: stable@vger.kernel.org
Cc: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Ismael Ferreras Morezuelas <swyterzone@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>