composer: Set acquire_fence to nullptr in PostCommit

In PostCommit stage, set acquire_fence of SDM layer buffer to nullptr.
Otherwise it gets programmed to driver in the subsequent draw cycles,
even when the layer is not updating.

Bug: 157715124
Test: SST, scrolling, app launching/closing, playing video
Change-Id: I2f77d11088528037e2d9199dfcb6571dd88a71f3
1 file changed