The intrinsic produces a vec2, so let's honor that and avoid the weird
lowering to scalar and later reconstruction to vec2 when we find
load vulkan descriptor intrinsics.
It fixes tests like this (which require that we expose KHR_spirv_1_4):
dEQP-VK.spirv_assembly.instruction.spirv1p4.opptrequal.null_comparisons_ssbo_equal
that otherwise produce bad code that tries to access a vec2 from the result of
that intrinsic, leading to NIR validation errors.
Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11257>
21b0a4c80c