[llvm] [llvm][ARM][CodeGen] Disable MEMCPY LDM/STM inlining for Cortex v7-m (PR #106378)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

It looks like later codegen passes opportunistically form ldrd/strd and ldm/stm, depending on the input values; do we want that?  Do we want to force ldrd/strd to be used more?

If we really just want plain load/store instructions, there's target-independent code to expand memcpy; we shouldn't duplicate it.

https://github.com/llvm/llvm-project/pull/106378