radv: Use before/after_cf_list for entrypoints

radv: Use before/after_cf_list for entrypoints

Via Coccinelle patch:

    @@
    expression shader;
    @@

    -nir_before_cf_list(&nir_shader_get_entrypoint(shader)->body)
    +nir_before_impl(nir_shader_get_entrypoint(shader))

    @@
    expression shader;
    @@

    -nir_after_cf_list(&nir_shader_get_entrypoint(shader)->body)
    +nir_after_impl(nir_shader_get_entrypoint(shader))

Suggested-by: Daniel Schürmann <daniel@schuermann.dev>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24910>