deprecation cleanup: remove leftover files

Several modules removal and deprecations occurred in 19.0.0 (initial
19 release), but associated UPGRADE files were not removed from
staging for some reason in the master branch.

This patch removes those files, and also removes a spurious leftover
header, chan_phone.h (associated module removed in 19).

Change-Id: Ib92142c846b45c882d6b2b6caca7225253c83add