msm: display: add more checking to ensure display is idle

Before execute operation on display, make sure it is complete idle
Because non-blocking display update has been introduced, need make sure
display update has finished in all entrances except the ones for
initialization.

Change-Id: I0660080262b7e5895f5f558c0a9f71aa84b9aa99
Signed-off-by: Ken Zhang <kenz@codeaurora.org>
Signed-off-by: Naseer Ahmed <naseer@codeaurora.org>