The early-Z test uses Z values produced from FEP, so when we write Z from a shader we need to disable EZ. However, there are some instances where want to write the FEP-Z from the shader, in which case we would not need to disable EZ. Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14037>