Set MaxAtomicSizeInBitsSupported for remaining targets. (#75703)

Targets affected:

- NVPTX and BPF: set to 64 bits.
- ARC, Lanai, and MSP430: set to 0 (they don't implement atomics).

Those which didn't yet add AtomicExpandPass to their pass pipeline now
do so.

This will result in larger atomic operations getting expanded to
`__atomic_*` libcalls via AtomicExpandPass. On all these targets, this
now matches what Clang already does in the frontend.

The only targets which do not configure AtomicExpandPass now are:
- DirectX and SPIRV: they aren't normal backends.
- AVR: a single-cpu architecture with no privileged/user divide, which
could implement all atomics by disabling/enabling interrupts, regardless
of size/alignment. Will be addressed by future work.