Revert "drm/i915: GFX_MODE Flush TLB Invalidate Mode must be '1' for scanline waits"

This reverts commit 39314361, which
was commit f05bb0c7 upstream.

This has been found to cause GPU hangs when backported to 3.2, though
not in mainline.

References: http://bugs.launchpad.net/bugs/1140716
Cc: Steve Conklin <sconklin@canonical.com>
Cc: Stefan Bader <stefan.bader@canonical.com>
Cc: Bradd Figg <brad.figg@canonical.com>
Cc: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -408,11 +408,6 @@ static int init_render_ring(struct intel_ring_buffer *ring)
 	if (INTEL_INFO(dev)->gen >= 6)
 		I915_WRITE(MI_MODE, GFX_MODE_ENABLE(ASYNC_FLIP_PERF_DISABLE));
 
-	/* Required for the hardware to program scanline values for waiting */
-	if (INTEL_INFO(dev)->gen == 6)
-		I915_WRITE(GFX_MODE,
-			   GFX_MODE_ENABLE(GFX_TLB_INVALIDATE_ALWAYS));
-
 	if (IS_GEN7(dev))
 		I915_WRITE(GFX_MODE_GEN7,
 			   GFX_MODE_DISABLE(GFX_TLB_INVALIDATE_ALWAYS) |