selftests: udpgro: no need to load xdp for gro

After commit d7db7775ea2e ("net: veth: do not manipulate GRO when using
XDP"), there is no need to load XDP program to enable GRO. On the other
hand, the current test is failed due to loading the XDP program. e.g.

# selftests: net: udpgro.sh
# ipv4
# no GRO ok
# no GRO chk cmsg ok
# GRO ./udpgso_bench_rx: recv: bad packet len, got 1472, expected 14720
#
# failed

[...]

# bad GRO lookup ok
# multiple GRO socks ./udpgso_bench_rx: recv: bad packet len, got 1452, expected 14520
#
# ./udpgso_bench_rx: recv: bad packet len, got 1452, expected 14520
#
# failed
ok 1 selftests: net: udpgro.sh

After fix, all the test passed.

# ./udpgro.sh
ipv4
no GRO ok
[...]
multiple GRO socks ok

Fixes: d7db7775ea2e ("net: veth: do not manipulate GRO when using XDP")
Reported-by: Yi Chen <[e-mail]>
Closes: https://issues.redhat.com/browse/RHEL-53858
Reviewed-by: Toke Høiland-Jørgensen <[e-mail]>
Acked-by: Paolo Abeni <[e-mail]>
Signed-off-by: Hangbin Liu <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

tools/testing/selftests/net/udpgro.sh

···
 
 readonly PEER_NS="ns-peer-$(mktemp -u XXXXXX)"
 
-BPF_FILE="xdp_dummy.bpf.o"
-
 # set global exit status, but never reset nonzero one.
 check_err()
 {
···
 	ip -netns "${PEER_NS}" addr add dev veth1 192.168.1.1/24
 	ip -netns "${PEER_NS}" addr add dev veth1 2001:db8::1/64 nodad
 	ip -netns "${PEER_NS}" link set dev veth1 up
-	ip -n "${PEER_NS}" link set veth1 xdp object ${BPF_FILE} section xdp
+	ip netns exec "${PEER_NS}" ethtool -K veth1 gro on
 }
 
 run_one() {
···
 	check_err $?
 	return $ret
 }
-
-if [ ! -f ${BPF_FILE} ]; then
-	echo "Missing ${BPF_FILE}. Run 'make' first"
-	exit -1
-fi
 
 if [[ $# -eq 0 ]]; then
 	run_all