UPSTREAM: bpf: use the same condition in perf event set/free bpf handler

This is a cleanup such that doing the same check in
perf_event_free_bpf_prog as we already do in
perf_event_set_bpf_prog step.

Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 0b4c6841fee03e096b735074a0c4aab3a8e92986)
Signed-off-by: Connor O'Brien <connoro@google.com>
Bug: 121213201
Bug: 138317270
Test: build & boot cuttlefish
Change-Id: Ie423e73a73be29e8ef50cc22dbb03e14e241c8de