IP metrics: update link layer mapping

Properly map transport nan and lowpan to their corresponding link layer
enum. Also do so for interface names

Bug: 34901696
Bug: 65439160
Test: runtest frameworks-net
Merged-In: I44a1cb3b6d21881b64adda7744360e4dfc519b12

(cherry picked from commit f7f7ed01)

Change-Id: Ic92b6d5c07404ea79f9a8975e8fc6925eaa10ba4