selftests: net: bump GRO timeout for gro/setup_veth

Commit 51bef03 ("selftests/net: deflake GRO tests") recently
switched to NAPI suspension, and lowered the timeout from 1ms to 100us.
This started causing flakes in netdev-run CI. Let's bump it to 200us.
In a quick test of a debug kernel I see failures with 100us, with 200us
in 5 runs I see 2 completely clean runs and 3 with a single retry
(GRO test will retry up to 5 times).

Reviewed-by: Kevin Krakauer <krakauer@google.com>
Link: https://patch.msgid.link/20250310110821.385621-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

tools/testing/selftests/net/setup_veth.sh

@@ -11,7 +11,7 @@ setup_veth_ns() {
 	local -r ns_mac="$4"
 
 	[[ -e /var/run/netns/"${ns_name}" ]] || ip netns add "${ns_name}"
-	echo 100000 > "/sys/class/net/${ns_dev}/gro_flush_timeout"
+	echo 200000 > "/sys/class/net/${ns_dev}/gro_flush_timeout"
 	echo 1 > "/sys/class/net/${ns_dev}/napi_defer_hard_irqs"
 	ip link set dev "${ns_dev}" netns "${ns_name}" mtu 65535
 	ip -netns "${ns_name}" link set dev "${ns_dev}" up