HWC2: Don't set null handle for client layers

Removes the code that explicitly set a null buffer handle for client
layers.

Test: Cherry-pick from internal branch
Bug: 29463310
Change-Id: I570e6041ba72d64971bb6c364e8e7b6f84eeff08
(cherry picked from commit 6be002845f9dd310679f8cb11fa9d9217f650e3b)
1 file changed