thunderbolt: Convert switch to a device

Thunderbolt domain consists of switches that are connected to each
other, forming a bus. This will convert each switch into a real Linux
device structure and adds them to the domain. The advantage here is
that we get all the goodies from the driver core, like reference
counting and sysfs hierarchy for free.

Also expose device identification information to the userspace via new
sysfs attributes.

In order to support internal connection manager (ICM) we separate switch
configuration into its own function (tb_switch_configure()) which is
only called by the existing native connection manager implementation
used on Macs.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com>
Reviewed-by: Michael Jamet <michael.jamet@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>