MessageQueue now correctly reports that an update is not required

MessageQueue now correctly reports that an update is not required

[Problem]  The message queue always reports that it has messages even if it does not.
[Cause]    The sceneUpdate counter never gets decremented to 0. This causes the update to run
           every time.
[Solution] It was being cleared within a for loop where messages are being processed, it should be
           outside this loop so is cleared if there are no messages.

Change-Id: I1d490c9c25f07813f2f904d659e5116e6b27a50c
Signed-off-by: Adeel Kazmi <adeel.kazmi@samsung.com>