drm/i915: Don't forget to mark crtc as inactive after disable

Watermark calculations depend on the intel_crtc->active flag to be set
properly. Suspend/resume is broken on SKL and we also get DDB mismatches
without this patch.

The regression was introduced in:

commit eddfcbcdc27fbecb33bff098967bbdd7ca75bfa6
Author: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Date:   Mon Jun 15 12:33:53 2015 +0200

    drm/i915: Update less state during modeset.

    No need to repeatedly call update_watermarks, or update_fbc.
    Down to a single call to update_watermarks in .crtc_enable

    Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
    Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
    Tested-by(IVB): Matt Roper <matthew.d.roper@intel.com>
    Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

v2: Don't touch disable_shared_dpll()

Signed-off-by: Patrik Jakobsson <patrik.jakobsson@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91203
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -5049,6 +5049,9 @@ static void ironlake_crtc_disable(struct drm_crtc *crtc)
 
 		ironlake_fdi_pll_disable(intel_crtc);
 	}
+
+	intel_crtc->active = false;
+	intel_update_watermarks(crtc);
 }
 
 static void haswell_crtc_disable(struct drm_crtc *crtc)
@@ -5094,6 +5097,9 @@ static void haswell_crtc_disable(struct drm_crtc *crtc)
 	for_each_encoder_on_crtc(dev, crtc, encoder)
 		if (encoder->post_disable)
 			encoder->post_disable(encoder);
+
+	intel_crtc->active = false;
+	intel_update_watermarks(crtc);
 }
 
 static void i9xx_pfit_enable(struct intel_crtc *crtc)
@@ -6158,6 +6164,9 @@ static void i9xx_crtc_disable(struct drm_crtc *crtc)
 
 	if (!IS_GEN2(dev))
 		intel_set_cpu_fifo_underrun_reporting(dev_priv, pipe, false);
+
+	intel_crtc->active = false;
+	intel_update_watermarks(crtc);
 }
 
 static void intel_crtc_disable_noatomic(struct drm_crtc *crtc)