selftests: net: Fix a typo in udpgro_fwd.sh

$rvs -> $rcv

Fixes: a062260a ("selftests: net: add UDP GRO forwarding self-tests")
Signed-off-by: Jianguo Wu <wujianguo@chinatelecom.cn>
Link: https://lore.kernel.org/r/d247d7c8-a03a-0abf-3c71-4006a051d133@163.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/udpgro_fwd.sh

@@ -132,7 +132,7 @@ run_test() {
 	local rcv=`ip netns exec $NS_DST $ipt"-save" -c | grep 'dport 8000' | \
 							  sed -e 's/\[//' -e 's/:.*//'`
 	if [ $rcv != $pkts ]; then
-		echo " fail - received $rvs packets, expected $pkts"
+		echo " fail - received $rcv packets, expected $pkts"
 		ret=1
 		return
 	fi