add Virgin Mobile USA apn

Change-Id: Ia016e19b14a173746fddbc5319fac98ca9f188c5

prebuilt/common/etc/apns-conf.xml

@@ -662,6 +662,7 @@
   <apn carrier="Credo Mobile" mcc="310" mnc="120" apn="n.w1.ispsn" type="default,mms" mmsc="http://mms.plspictures.com" mmsproxy="68.28.31.7" mmsport="80" protocol="IPV4V6" roaming_protocol="IPV4V6" />
   <apn carrier="Ting" mcc="310" mnc="120" apn="n.t8.ispsn" type="default,mms" mmsc="http://mms.plspictures.com" mmsproxy="68.28.31.7" mmsport="80" protocol="IPV4V6" roaming_protocol="IPV4V6" />
   <apn carrier="FreedomPop" mcc="310" mnc="120" apn="n.f6.ispsn" type="default,mms" mmsc="http://mms.sprintpcs.com" mmsproxy="68.28.31.7" mmsport="80" protocol="IPV4V6" roaming_protocol="IPV4V6" />
+  <apn carrier="Virgin Mobile" mcc="310" mnc="120" apn="n.vmu.ispsn" user="Sprint" password="*" mmsproxy="68.28.31.7" mmsport="80" mmsc="http://mmsc.vmobl.com:8088/mms?" type="default,supl,mms,fota,dun" />
   <apn carrier="My Multi Media" mcc="310" mnc="130" apn="mms.c1.ama" user="cell1mms" password="cell1" mmsc="http://mms.iot1.com/amarillo/mms.php" type="mms" />
   <apn carrier="Cricket AIO" mcc="310" mnc="150" apn="ndo" mmsc="http://mmsc.aiowireless.net" mmsproxy="proxy.aiowireless.net" mmsport="80" type="default,mms,fota,supl" />
   <apn carrier="T-Mobile US 160" mcc="310" mnc="160" apn="epc.tmobile.com" user="none" password="none" server="*" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" type="default,supl,mms" />