glsl: Drop exec_list argument to lower_ubo_reference

glsl: Drop exec_list argument to lower_ubo_reference

We always pass in shader->ir and we already pass in the shader, so just
drop the exec_list. Most passes either take just a exec_list or a
shader, so this seems more consistent.

Reviewed-by: Timothy Arceri <timothy.arceri@collabora.com>
Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Signed-off-by: Kristian Høgsberg Kristensen <krh@bitplanet.net>