bpftool: Update the bash completion(add autoattach to prog load)

Add autoattach optional to prog load|loadall for supporting
one-step load-attach-pin_link.

Signed-off-by: Wang Yufen <wangyufen@huawei.com>
Link: https://lore.kernel.org/r/1665736275-28143-4-git-send-email-wangyufen@huawei.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: wangyufen316

tools/bpf/bpftool/bash-completion/bpftool

@@ -505,6 +505,7 @@ _bpftool()
                             _bpftool_once_attr 'type'
                             _bpftool_once_attr 'dev'
                             _bpftool_once_attr 'pinmaps'
+                            _bpftool_once_attr 'autoattach'
                             return 0
                             ;;
                     esac