Instead of calling cls_bpf_get() in a loop to find
a unused handle, just switch to idr API to allocate
new handles.
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Chris Mi <redacted>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <redacted>