Mms: The cursor should be on the edit box after tap next

If the message list is not empty,user add message subject and edit
it, then click next button,the messagelist will get the focus.

Let the message TextEdit get focus when click the next button.

CRs-Fixed: BZ1090

Change-Id: I6c3d704fb337d3edcd65a5a8a1e7b878e2335994