wwan/ofono: fix a couple of logic errors in update_connection_list()
requested to merge peat-psuwit/NetworkManager:for-upstream/ofono-fix-update-connection-list into main
- Only consider preferred context of "internet" type. There can be multiple preferred contexts of multiple types, and we care about "internet" type only.
- Don't check for "internet+mms" type. It turns out that "internet+mms" isn't a thing in oFono, and is used to represent "internet" context with MMSC in the lomiri-system-setting's UI only.
Fixes: 9fc72bf7 ('wwan/ofono: create connections based on available contexts') Bug-UBports: https://gitlab.com/ubports/development/core/packaging/network-manager/-/issues/3