st/nine: Enable ttn cache

A trace of a Hat in Time, which builds thousands of shaders
takes 339 seconds to run the second time without this patch,
and 41 seconds with it (basically there is no more loading times).

Signed-off-by: Axel Davy <davyaxel0@gmail.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <mesa/mesa!4993>