drm/msm/sde: reuse rotator from previous crtc states

Current crtc resource pool only searches for hw resource
in the current resource pool state. If a resource is no
longer needed, it will be released in the next state.
If the same resource is needed in subsequent state, it
has to wait until the resource is fully released and
returned to the global resource pool. To speed up the
reacquisition process, the resource pool search algorithm
is extended to search resources in previous states which
are still outstanding and not destroyed yet.

Change-Id: I841ea07fa4d1a72a93b8d94e71e32ddc4b45212f
Signed-off-by: Alan Kwong <akwong@codeaurora.org>