Tighten condition for calling checkMobileProvisioning.

Add the condition that the connected network needs to be TYPE_MOBILE.
This eliminates checking on connecting to secondary networks like
FOTA, MMS, SUPL ...

This reduces unnecessary attempts to bring up multiple connections at
the same time. Especially in the light of the trouble we're having with HFA
on Sprint, where we don't want to connect to any other network until HFA
has completed.

Bug: 10758001
Change-Id: Id294536b70304a51de4752bc1a4ffac734f10f1a