[SLP]Fix unscheduled-deps assert for operands of copyable user lanes
When every copyable model of an edge is skipped because the user is
itself a copyable lane, the instruction's own schedule data still
carries the def-use dependency counted by calculateDependencies. Release
it instead of returning early just because copyable data was found.
Fixes https://github.com/llvm/llvm-project/pull/213369#issuecomment-5189475412
Reviewers:
Pull Request: https://github.com/llvm/llvm-project/pull/214283