selftests: rtnetlink: correct xfrm policy rule in kci_test_ipsec_offload

When testing in kci_test_ipsec_offload, srcip is configured as $dstip,
it should add xfrm policy rule in instead of out.
The test result of this patch is as follows:
PASS: ipsec_offload

Fixes: 2766a111 ("selftests: rtnetlink: add ipsec offload API test")
Signed-off-by: NZhengchao Shao <shaozhengchao@huawei.com>
Acked-by: NHangbin Liu <liuhangbin@gmail.com>
Link: https://lore.kernel.org/r/20221201082246.14131-1-shaozhengchao@huawei.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/rtnetlink.sh

@@ -782,7 +782,7 @@ kci_test_ipsec_offload()
 	    tmpl proto esp src $srcip dst $dstip spi 9 \
 	    mode transport reqid 42
 	check_err $?
-	ip x p add dir out src $dstip/24 dst $srcip/24 \
+	ip x p add dir in src $dstip/24 dst $srcip/24 \
 	    tmpl proto esp src $dstip dst $srcip spi 9 \
 	    mode transport reqid 42
 	check_err $?