drm/msm/dpu: Remove suspend state tracking from crtc

Since drm core's modeset locks serialize atomic commits, we don't need to
track whether or not we're in a suspended state from inside the crtc for
dpu_crtc_enable/disable. This patch removes the suspend logic from the crtc and
removes the relevant tracing from dpu_trace. Since we removed all calls
to dpu_kms_is_suspend_state, we can remove that function and the
suspend_state field of dpu_kms as well.

v2: added patch to patchset
v3: reworded commit body and moved deletion of dpu_kms_is_suspend_state and
suspend_state to this patch

Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Bruce Wang <bzwang@chromium.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>