drm/i915: Kill crtc->plane checks from the primary plane update hooks

These were apparently meant to protect the SAREA which only has
room for two pipes, but things clearly went a bit wonky when
first the .update_plane() hooks were split up and then pipe C
got introduced.

The checks actually protecting the SAREA live in
intel_crtc_update_sarea() these days, so the checks in the primary
plane update hooks are just historical leftovers which are to be
eliminated.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -2166,15 +2166,6 @@ static int i9xx_update_primary_plane(struct drm_crtc *crtc,
 	u32 dspcntr;
 	u32 reg;
 
-	switch (plane) {
-	case 0:
-	case 1:
-		break;
-	default:
-		DRM_ERROR("Can't update plane %c in SAREA\n", plane_name(plane));
-		return -EINVAL;
-	}
-
 	intel_fb = to_intel_framebuffer(fb);
 	obj = intel_fb->obj;
 
@@ -2267,16 +2258,6 @@ static int ironlake_update_primary_plane(struct drm_crtc *crtc,
 	u32 dspcntr;
 	u32 reg;
 
-	switch (plane) {
-	case 0:
-	case 1:
-	case 2:
-		break;
-	default:
-		DRM_ERROR("Can't update plane %c in SAREA\n", plane_name(plane));
-		return -EINVAL;
-	}
-
 	intel_fb = to_intel_framebuffer(fb);
 	obj = intel_fb->obj;