Fix duplicate user confirmations for a multi-part SMS

SmsTracker array is used in SMSDispatcher for a single and a multi-part
SMS in common so that user confirmation is required once always and all
the parts for a message can be failed together.

Test: Manual

Change-Id: Ia494ed1b51ea76c3d72f224159e3b429c9010385
Signed-off-by: Taesu Lee <taesu82.lee@samsung.com>