bpf, vsock: Invoke proto::close on close()

bpf, vsock: Invoke proto::close on close()

vsock defines a BPF callback to be invoked when close() is called. However,
this callback is never actually executed. As a result, a closed vsock
socket is not automatically removed from the sockmap/sockhash.

Introduce a dummy vsock_close() and make vsock_release() call proto::close.

Note: changes in __vsock_release() look messy, but it's only due to indent
level reduction and variables xmas tree reorder.

Fixes: 634f1a7110b4 ("vsock: support sockmap")
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Luigi Leonardi <leonardi@redhat.com>
Link: https://lore.kernel.org/r/20241118-vsock-bpf-poll-close-v1-3-f1b9669cacdc@rbox.co
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>