Make "Mark all as Read" context sensitive

This commit make the mark all as read option only show
when you have unread conversations and not at all times
similar to the behavior of delete all threads option.

Change-Id: I0de7967f14f67b4938a32afccdf05d033a5599aa
Mms: Show menu option to delete all messages

Delete all messages option is not visible in "Manage SIM card messages"
so unable to delete all SIM card messages at a time.
Use invalidate menu options to show "Delete all messages" option.

Change-Id: I77645f51bffe2ca9718f81483e93e3bf925f293a