drm_hwcomposer: use HWC_FRAMEBUFFER_TARGET if all HWC_OVERLAY layers are skipped

Apparently there are cases (such as during rotation) where SF will put content
in framebuffer target and set HWC_SKIP_LAYER on all other layers. In this case
we need to use the HWC_FRAMEBUFFER_TARGET layer.

BUG=23936827
TEST=verify on ryu that rotation works

Change-Id: Ice8ee5a023a92fc286dbf837a822fa6f6c0fde6b
1 file changed