selftests: forwarding: Fix ping failure due to short timeout

The tests send 100 pings in 0.1 second intervals and force a timeout of
11 seconds, which is borderline (especially on debug kernels), resulting
in random failures in netdev CI [1].

Fix by increasing the timeout to 20 seconds. It should not prolong the
test unless something is wrong, in which case the test will rightfully
fail.

[1]
# selftests: net/forwarding: vxlan_bridge_1d_port_8472_ipv6.sh
# INFO: Running tests with UDP port 8472
# TEST: ping: local->local [ OK ]
# TEST: ping: local->remote 1 [FAIL]
# Ping failed
[...]

Fixes: b07e9957f220 ("selftests: forwarding: Add VxLAN tests with a VLAN-unaware bridge for IPv6")
Fixes: 728b35259e28 ("selftests: forwarding: Add VxLAN tests with a VLAN-aware bridge for IPv6")
Reported-by: Paolo Abeni <[e-mail]>
Closes: https://lore.kernel.org/netdev/[e-mail]/
Signed-off-by: Ido Schimmel <[e-mail]>
Reviewed-by: Hangbin Liu <[e-mail]>
Reviewed-by: Jiri Pirko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

tools/testing/selftests/net/forwarding/vxlan_bridge_1d_ipv6.sh

···
 
 	# Send 100 packets and verify that at least 100 packets hit the rule,
 	# to overcome ARP noise.
-	PING_COUNT=100 PING_TIMEOUT=11 ping_do $dev $dst_ip
+	PING_COUNT=100 PING_TIMEOUT=20 ping_do $dev $dst_ip
 	check_err $? "Ping failed"
 
 	tc_check_at_least_x_packets "dev $rp1 egress" 101 10 100
···
 
 	# Send 100 packets and verify that at least 100 packets hit the rule,
 	# to overcome neighbor discovery noise.
-	PING_COUNT=100 PING_TIMEOUT=11 ping6_do $dev $dst_ip
+	PING_COUNT=100 PING_TIMEOUT=20 ping6_do $dev $dst_ip
 	check_err $? "Ping failed"
 
 	tc_check_at_least_x_packets "dev $rp1 egress" 101 100

tools/testing/selftests/net/forwarding/vxlan_bridge_1q_ipv6.sh

···
 
 	# Send 100 packets and verify that at least 100 packets hit the rule,
 	# to overcome ARP noise.
-	PING_COUNT=100 PING_TIMEOUT=11 ping_do $dev $dst_ip
+	PING_COUNT=100 PING_TIMEOUT=20 ping_do $dev $dst_ip
 	check_err $? "Ping failed"
 
 	tc_check_at_least_x_packets "dev $rp1 egress" 101 10 100
···
 
 	# Send 100 packets and verify that at least 100 packets hit the rule,
 	# to overcome neighbor discovery noise.
-	PING_COUNT=100 PING_TIMEOUT=11 ping6_do $dev $dst_ip
+	PING_COUNT=100 PING_TIMEOUT=20 ping6_do $dev $dst_ip
 	check_err $? "Ping failed"
 
 	tc_check_at_least_x_packets "dev $rp1 egress" 101 100