freedreno/ir3: fix constlen versus indirect UBO

freedreno/ir3: fix constlen versus indirect UBO

If we access the address of the UBO indirectly, and there is no higher
const emitted w/ direct access (like an immediate lowered to uniform)
the assembler won't figure out the correct constlen.

Fixes:
  dEQP-GLES31.functional.shaders.opaque_type_indexing.ubo.uniform_vertex
  dEQP-GLES31.functional.shaders.opaque_type_indexing.ubo.uniform_fragment
  dEQP-GLES31.functional.shaders.opaque_type_indexing.ubo.dynamically_uniform_vertex
  dEQP-GLES31.functional.shaders.opaque_type_indexing.ubo.dynamically_uniform_fragment

Signed-off-by: Rob Clark <robdclark@chromium.org>