[mlir][opt] Expose MLIR_ENABLE_DEPRECATED_GPU_SER... in mlir-config.h. (#84006)

This is another follow-up of #83004, which made the same change for
`MLIR_CUDA_CONVERSIONS_ENABLED`. As the previous PR, this PR commit
exposes mentioned CMake variable through `mlir-config.h` and uses the
macro that is introduced with the same name. This replaces the macro
`MLIR_ENABLE_DEPRECATED_GPU_SERIALIZATION`, which the CMake files
previously defined manually.