vc4: Fix early Z behavior on hardware.

It turns out the simulator was not treating this bit the same as the RPi,
and I'd forgotten to remove it when turning on early Z.  The result was
that you'd get big chunks of your rendering missing.

src/gallium/drivers/vc4/vc4_context.c

@@ -151,8 +151,7 @@ vc4_setup_rcl(struct vc4_context *vc4)
                             VC4_RENDER_CONFIG_MEMORY_FORMAT_SHIFT) |
                            (vc4_rt_format_is_565(render_surf->base.format) ?
                             VC4_RENDER_CONFIG_FORMAT_BGR565 :
-                            VC4_RENDER_CONFIG_FORMAT_RGBA8888) |
-                           VC4_RENDER_CONFIG_EARLY_Z_COVERAGE_DISABLE));
+                            VC4_RENDER_CONFIG_FORMAT_RGBA8888)));
 
         /* The tile buffer normally gets cleared when the previous tile is
          * stored.  If the clear values changed between frames, then the tile