Modify APN for "Mobile TeleSystems" Russia

IPv4v6 support was added to main APN "internet.mts.ru" for "Mobile TeleSystems" Russia (mcc="250", mnc="01")

<apn carrier="MTS Internet"
      mcc="250"
      mnc="01"
      apn="internet.mts.ru"
      user="mts"
      password="mts"
      authtype="1"
      type="default,supl"
      protocol="IPV4V6"
      roaming_protocol="IPV4V6"
  />

Change-Id: I1b651941129ecff2ccdbc6dabbff5d5a587029ce