Add a default MMS UA Profile URL

Companion change to I8a648014873319ea0d0f1089495d6777b8a1b8bf,
config_mms_user_agent_profile_url can't be empty either

Change-Id: Ib6b34972439818da47c389377664e75263dfd21b
Merge branch 'cm-11.0' of git://github.com/CyanogenMod/android_vendor_cm into cd-4.4