Use the param type, not the referenced variable. The referenced variable
can be a structure, which wouldn't be recognized as a sampler or image.
Fixes: 733bee57eb - glsl: lower samplers with highp coordinates correctly
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Tested-by: Dieter Nützel Dieter@nuetzel-hh.de on gfx8 (Polaris 20)
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34959>
(cherry picked from commit bd5d623674)