vendor/cm: fix Sprint MMS apn being set as default

Sprint CDMA MMS APN was being incorrectly set as default and hipri,
causing LTE connectivity issues because it was prioritized over the
other APN entries for LTE and EHRPD.

Change-Id: I6ca4fd172e2ecc64ca7a2c3fbca5327be61e7b5c
merge changes from CyanogenMod 10.2 into local branch