[RISCV] Prefer Zcmp push/pop instead of save-restore calls. (#66046)

Zcmp push/pop can reduce more code size then save-restore calls. There
are two reasons,
1. Call for save-restore calls needs 4-8 bytes, but Zcmp push/pop only
needs 2 bytes.
2. Zcmp push/pop can also handles small shift of sp.