st/glsl: make sure to propagate initialisers to driver storage

This essentially reverts 20234cfe.

Fixes piglit test:
tests/spec/arb_get_program_binary/execution/uniform-after-restore.shader_test

Fixes: 20234cfe "st/mesa: don't propagate uniforms when restoring from cache"

Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110784
(cherry picked from commit fea36a8f)