usb: typec: Consolidate sysfs ABI documentation

Both partner and cable have identity VDOs. These are listed separately
in the Documentation/ABI/testing/sysfs-class-typec. Factor these out
into a common location to avoid the duplication.

Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Prashant Malani <pmalani@chromium.org>
Link: https://lore.kernel.org/r/20201125084911.1077462-1-pmalani@chromium.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>