Fix *86 converting issue

Our design is to convert *86 to +1MDN, using real MDN to replace string 'MDN'.
When phone roaming in GSM/UMTS network, MDN is grabbed from sim card's EF_MSISDN,
here the EF_MSISDN is +1XXXXX, so after converting, the number is changed to
+1+1XXXXX, and finally the second + and following part will be removed in
number format checking

Bug: 17822591
Change-Id: I9b0cf822b4f4dc244061f23249d150af237df372