hwc: Reset previous width and height

If the current YUV count is 0 previous width and height
needs to be reset.

If FLIP is required then do not use rotator for resolution change.

Change-Id: I601cee2eddcf304b9c94d3def19d603c04b18ceb
libhwcomposer: Don't reset cached layer handle on MDP comp

Layer handle values will always be stored irrespective of the
composition type. Layer caching will choose a layer for FB
composition if it's handle has not changed.

Change-Id: Ied42d6ecafe48a9240aacc2d172b7d81b0d42a5d