Assume the callers lock everything with drm_modeset_lock_all.

This change had to be done after converting suspend/resume to
use atomic_state so the atomic state is preserved, otherwise
all transitional state is erased.

Now all callers of .crtc_enable and .crtc_disable go through
atomic modeset! :-D

Changes since v1:
- Only check for crtc_state->active in valleyview_modeset_global_pipes.
- Only check for crtc_state->active in modeset_update_crtc_power_domains.
Changes since v2:
- Rework on top of the changed patch order.
Changes since v3:
- Rename intel_crtc_toggle in description to *_control
- Change return value to int.
- Do not add plane state, should be done implicitly already.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>