selftests/bpf: Simplify the calculation of variables

Fix the following coccicheck warnings:

./tools/testing/selftests/bpf/test_sockmap.c:735:35-37: WARNING !A || A
&& B is equivalent to !A || B.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/1614757930-17197-1-git-send-email-jiapeng.chong@linux.alibaba.com

tools/testing/selftests/bpf/test_sockmap.c

@@ -732,7 +732,7 @@ static int sendmsg_test(struct sockmap_options *opt)
 		 * socket is not a valid test. So in this case lets not
 		 * enable kTLS but still run the test.
 		 */
-		if (!txmsg_redir || (txmsg_redir && txmsg_ingress)) {
+		if (!txmsg_redir || txmsg_ingress) {
 			err = sockmap_init_ktls(opt->verbose, rx_fd);
 			if (err)
 				return err;