Update prebuilt/common/etc/apns-conf.xml

Hi,

I've just found an issue in the "apns-conf.xml" file. The entry for my provider "LuxGSM" impedes MMS to work.

In order to fix this, you'd need to replace :

<apn carrier="Luxgsm Internet" mcc="270" mnc="01" apn="web.pt.lu" type="default,supl,mms" />

By :

<apn carrier="LUXGSM MMS" mcc="270" mnc="01" apn="mms.pt.lu" user="mms" password="mms" mmsc="http://mmsc.pt.lu" mmsproxy="194.154.192.88" mmsport="8080" type="mms" />
<apn carrier="LUXGSM WEB" mcc="270" mnc="01" apn="web.pt.lu" user="web" password="web" type="default,supl" />

JP.