Make sure to cast with the deref type that contains more information
than the returned type because it's valid in SPIR-V.
This fixes dEQP-VK.binding_model.descriptor_heap.graphics.*_vectors and
also the PositiveGpuAV.HeapWithUntypedPointers VVL test.
Cc: mesa-stable
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
(cherry picked from commit 975ae01208)
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/41540>