us: add "fast.t-mobile.com" APN for T-Mobile

The "fast.t-mobile.com" APN accommodates LTE plus what the
"epc.tmobile.com" APN already supports.

BUG=chromium:342569
TEST=Tested the following:
1. `xmllint --valid --noout serviceproviders.xml`
2. Run unit tests.
3. Connect to T-Mobile using Gobi2k, Gobi3k, Y3300, Y3400, and MU736.

Change-Id: Ie8946939206c7057f6d1b6da2e489f746bdd938d
Reviewed-on: https://chromium-review.googlesource.com/185736
Reviewed-by: Thieu Le <thieule@chromium.org>
Commit-Queue: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
1 file changed