drm/exynos: Remove apply manager callback

drm/exynos: Remove apply manager callback

This patch removes the apply() manager callback in favor of putting the
relevant commits in the individual drivers. This will mitigate some of
the difference between the suspend/resume path and the dpms path

Signed-off-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>