[CUDA][NFC] Remove build warnings for libdevice for NVPTX

[hdelan]

Remove some build warnings for libdevice for NVPTX.

Ping @MartinWehking

[hdelan]

Removes these build warnings:

[120/124] Generating ../../lib/libsycl-fallback-imf.new.o
clang-19: warning: ignoring '-fno-sycl-libspirv' option as it is not currently supported for target 'spir64_x86_64-unknown-unknown' [-Woption-ignored]
clang-19: warning: ignoring '-fno-sycl-libspirv' option as it is not currently supported for target 'spir64_gen-unknown-unknown' [-Woption-ignored]
clang-19: warning: ignoring '-fno-sycl-libspirv' option as it is not currently supported for target 'spir64_fpga-unknown-unknown' [-Woption-ignored]
clang-19: warning: ignoring '-fno-sycl-libspirv' option as it is not currently supported for target 'spir64-unknown-unknown' [-Woption-ignored]
clang-19: warning: ignoring '-fno-sycl-libspirv' option as it is not currently supported for target 'spirv64-unknown-unknown' [-Woption-ignored]
clang-19: warning: '-fno-sycl-libspirv' should not be used with target 'nvptx64-nvidia-cuda'; libspirv is required for correct behavior [-Wno-libspirv-hip-cuda]
clang-19: warning: argument unused during compilation: '-fno-bundle-offload-arch' [-Wunused-command-line-argument]