Revert "drm/i915: Only enable the plane after setting the fb base (pre-ILK)"

This reverts commit 49183b28.

Quoth Franz Melchior:

  "This patch introduces a bug on my infamous "Acer Travelmate
   5735Z-452G32Mnss": when KMS takes over, the frame buffer contents get
   completely garbled up on screen, with colored stripes and unreadable
   text (photo on request).  Only when X11 is started, the screen gets
   restored again.  Closing and re-opening the lid partly cures the
   mess, too: it makes the font readable, though horizontally stretched."
Acked-by: NKeith Packard <keithp@keithp.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/gpu/drm/i915/intel_display.c

@@ -5154,6 +5154,8 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
 
 	I915_WRITE(DSPCNTR(plane), dspcntr);
 	POSTING_READ(DSPCNTR(plane));
+	if (!HAS_PCH_SPLIT(dev))
+		intel_enable_plane(dev_priv, plane, pipe);
 
 	ret = intel_pipe_set_base(crtc, x, y, old_fb);