The reason waiting vblank is to be power gated and disabled clocks after
dma operation is completed. The dma operation is stopped already before
be power gated and clocks are disabled when mixer is disabled by commit
381be025("drm/exynos: stop mixer before gating clocks during
poweroff"). Don't need to wait vblank anymore.
Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>