mesa: stop assigning unused storage for non-bindless opaque types
The storage was once used by get_sampler_uniform_value() but that
was fixed long ago to use the uniform storage assigned by the
linker.
By not assigning storage for images/samplers the constant buffer
for gallium drivers will be reduced which could result in small
perf improvements.
V2: rebase on ARB_bindless_texture
Reviewed-by:
Samuel Pitoiset <samuel.pitoiset@gmail.com>