thunderbolt: Factor common ICM add and update operations out

thunderbolt: Factor common ICM add and update operations out

BugLink: http://bugs.launchpad.net/bugs/1730775
The newer ICM will not use link and depth to address devices. Instead it
uses route strings. In order to take advantage of the existing code
factor out common operations so that we can use the same functions with
the new ICM as well.

No functional changes intended.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
(cherry picked from commit ee487dd2447a43dd318bd7ba2c54e59e707ad851 linux-next)
Signed-off-by: Anthony Wong <anthony.wong@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>