vfs: make lchmod update symlink mode

Use a non-following provider operation for lchmod so it updates the
symbolic link metadata instead of changing the target file mode.

Signed-off-by: Kamat, Trivikram <16024985+trivikr@users.noreply.github.com>
Assisted-by: openai:gpt-5.5
PR-URL: #64350
Fixes: #64349
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

Author: trivikr