evita: default to MTP USB mode

You can't default to ADB since user is required to enable USB debugging
before adb kicks in. UMS was deprecated to help save users from
themselves (unclean unmounts and apps left wondering what happened to
their storage volume). We should at least default to MTP, even if users
will opt to change this later.

Change-Id: I534091a5fb64dc02c4bb31485714d990fb7c1931
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_device_htc_evita into cd-4.4