HWC2: Hook up to BoardConfig variable

Uses TARGET_USES_HWC2 to enable the HWC2 code path in SurfaceFlinger

Test: Cherry-pick from internal branch
Bug: 27211042
Change-Id: I7b7e3e3f7a918e74df0be27418196c81b4332564
(cherry picked from commit 8beb15f220fa7bb6a64235b509c818ecf1d45d81)
1 file changed