When the user sets a GSM or CDMA setting along with a Bluetooth setting
we know we're dealing with a DUN profile. No need to ask.

[thaller@redhat.com: verify() and normalize() must strongly agree whether a
connection is normalizable, and now to do it. That is, after verify()
determines the connection is normalizable, normalize() must fix it as
anticipated.

The reason is, we only want to modify the connection, if we are able
to create a valid result. Hence, after normalize() it *must* verify().

Try to simplify that by moving the logic of fixing the bt-type to a
common place _nm_connection_detect_bluetooth_type().]

Co-Authored-By: Thomas Haller <thaller@redhat.com>