Use the SubId in the TM.getNetworkType if Valid

If the TM instance has a specific subid that was
added using TM.createForSubscriptionId(), honor that
subId in getNetworkType().

Bug: 132466954
Test: compilation + manual
Merged-In: Ice4f673750ab3b374644750113e5b9b2a4f5ba63
Change-Id: Ice4f673750ab3b374644750113e5b9b2a4f5ba63
(cherry picked from commit 0aca4313)