[SPIR] Do not warn on 64-bit atomics (#185502)
Summary:
SPIR-V's Int64Atomics capability is not dependent on its addressing mode
as far as I am aware. These 32-bit SPIR targets already claim to support
the cl_khr_int64 atomics and we already emit 64-bit atomics in the
backend. Additionally, this is already accepted as a hack due to the
fact that the host will increase it in offloading usage. I do not see a
reason to keep these at 32, which causes numerous warnings inside of the
`libclc` build.
