hwc: Clear overlay and layer-rot map from caller

Clear overlay and layer-rot map from the top level caller of
composition, rather than from the place of actual intermediate
failure. This makes sure, even in cases of GPU comp failure,
overlay and layer-rot maps are cleared and eventually pipes unset.

Change-Id: Ibf1152a0e8ca66d87bcc6b87009c4b09e451099d
3 files changed