Add a new settings to device/sample/etc/apns-full-conf.xml for Truphone:

DUN must be added because there are other profiles who don't permit
it and are overlaping our settings

Test: Added the settings above to /etc/apns-conf.xml on a Nexus 5X
(Android 7.0) with root access.
Test: Inserted a Truphone SIM with the new MCC/MNC
Test: Reset the APN settings
Test: Verified that the APN was automatically populated with the
truphone.com APN
Test: Verified that the data sessions were automatically configured
Test: Activated the Portable Wi-Fi Hotspot funcionality.
Test: Verified that was possible to use the shared connection from
another device to navigate on the internet.

Change-Id: Idc8df4b961326e5c331ea88f56ad4a3647a5c3b6
Signed-off-by: Tiago Vaz <tiago.vaz@truphone.com>