[SPARC][IAS] Handle the case of non-4-byte aligned writeNopData

If the Count passed into writeNopData is not a multiple of four,
add a little amount of zeros before writing the NOP stream.
This makes it match the behavior of GNU binutils.

Reviewers: brad0, rorth, s-barannikov, jrtc27

Reviewed By: s-barannikov

Pull Request: https://github.com/llvm/llvm-project/pull/94251