clover/spirv: Don't call llvm::regularizeLlvmForSpirv

writeSpirv() already takes care of that, and calling it twice seems to
duplicate functions and cause problems when processing execution modes.

Fixes: 2043c5f37cf "clover/llvm: Add functions for compiling from..."
Acked-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Pierre Moreau <dev@pmoreau.org>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6306>