mesa: call FLUSH_VERTICES before changing sampler uniforms

Fixes: 9545139ce5f "mesa: skip FLUSH_VERTICES() if no samplers were changed"

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6946>
(cherry picked from commit 0a2117bc9e01bc821a6f766c516665d2aa5b47d8)
2 files changed