[llvm] [M68k] always use movem for register spills (PR #106715)

[Jessica Clarke via llvm-commits]

jrtc27 wrote:

The commit message should have the "why" beyond linking to issue numbers. From my own research the "why" appears to be because MOVE will set condition codes, but MOVEM will not. It also appears you're conflating two changes here: one involving using MOVEM over MOVE, and one involving not promoting registers and overflowing the stack space allocated to them.

https://github.com/llvm/llvm-project/pull/106715