drm/i915: Use 32bit read for BB_ADDR

The BB_ADDR register is documented to be 32bits at least since SNB.
Prior to that the high 32bits were listed as MBZ, so using a 64bit read
doesn't seem worth anything. Also the simulator doesn't like the 64bit
read. So just switch to using a 32bit read instead.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gpu_error.c

@@ -726,7 +726,7 @@ static void i915_record_ring_state(struct drm_device *dev,
 		error->instdone[ring->id] = I915_READ(RING_INSTDONE(ring->mmio_base));
 		error->instps[ring->id] = I915_READ(RING_INSTPS(ring->mmio_base));
 		if (ring->id == RCS)
-			error->bbaddr = I915_READ64(BB_ADDR);
+			error->bbaddr = I915_READ(BB_ADDR);
 		error->bbstate[ring->id] = I915_READ(RING_BBSTATE(ring->mmio_base));
 	} else {
 		error->faddr[ring->id] = I915_READ(DMA_FADD_I8XX);