v3d: Use the early_fragment_tests flag for the shader's disable-EZ field.

Apparently we need disable-EZ flagged, not just "does Z writes".

Fixes
dEQP-GLES31.functional.image_load_store.early_fragment_tests.no_early_fragment_tests_depth_fbo
on 7278, even though it passed in simulation.

Signed-off-by: Eric Anholt <eric@anholt.net>
Fixes: 051a41d3 ("v3d: Add support for the early_fragment_tests flag.")
(cherry picked from commit cd5e0b27)