thunderbolt: Switch CL states from enum to a bitmask

This is more natural and follows the hardware register layout better.
This makes it easier to see which CL states we enable (even though they
should be enabled together). Rename 'clx_mask' to 'clx' everywhere as
this is now always bitmask.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>