Fix functions that return undefined values. These issues were caught by
running clang using LLVM=1 option.

Clang warnings are as follows:
ovpn-cli.c:1587:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
 1587 |         if (!sock) {
      |             ^~~~~
ovpn-cli.c:1635:9: note: uninitialized use occurs here
 1635 |         return ret;
      |                ^~~
ovpn-cli.c:1587:2: note: remove the 'if' if its condition is always false
 1587 |         if (!sock) {
      |         ^~~~~~~~~~~~
 1588 |                 fprintf(stderr, "cannot allocate netlink socket\n");
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1589 |                 goto err_free;
      |                 ~~~~~~~~~~~~~~
 1590 |         }
      |         ~
ovpn-cli.c:1584:15: note: initialize the variable 'ret' to silence this warning
 1584 |         int mcid, ret;
      |                      ^
      |                       = 0
ovpn-cli.c:2107:7: warning: variable 'ret' is used uninitialized whenever switch case is taken [-Wsometimes-uninitialized]
 2107 |         case CMD_INVALID:
      |              ^~~~~~~~~~~
ovpn-cli.c:2111:9: note: uninitialized use occurs here
 2111 |         return ret;
      |                ^~~
ovpn-cli.c:1939:12: note: initialize the variable 'ret' to silence this warning
 1939 |         int n, ret;
      |                   ^
      |

Fixes: 959bc330a439 ("testing/selftests: add test tool and scripts for ovpn module")
Signed-off-by: Sidharth Seela <sidharthseela@gmail.com>
---
v6:
	- Remove stray line near Fixes tag.
	- Include ovpn prefix in commit message.

v5:
	- Assign -ENOMEM to ret inside if block.
	- Assign -EINVAL to ret inside case block.
v4:
	- Move changelog below sign-off.
	- Remove double-hyphens in commit description.
v3:
	- Use prefix net.
	- Remove so_txtime fix as default case calls error().
	- Changelog before sign-off.
	- Three dashes after sign-off
v2:
	- Use subsystem name "net".
	- Add fixes tags.
	- Remove txtimestamp fix as default case calls error.
	- Assign constant error string instead of NULL.

diff --git a/tools/testing/selftests/net/ovpn/ovpn-cli.c b/tools/testing/selftests/net/ovpn/ovpn-cli.c
index 9201f2905f2c..8d0f2f61923c 100644
--- a/tools/testing/selftests/net/ovpn/ovpn-cli.c
+++ b/tools/testing/selftests/net/ovpn/ovpn-cli.c
@@ -1586,6 +1586,7 @@ static int ovpn_listen_mcast(void)
 	sock = nl_socket_alloc();
 	if (!sock) {
 		fprintf(stderr, "cannot allocate netlink socket\n");
+		ret = -ENOMEM;
 		goto err_free;
 	}
 
@@ -2105,6 +2106,7 @@ static int ovpn_run_cmd(struct ovpn_ctx *ovpn)
 		ret = ovpn_listen_mcast();
 		break;
 	case CMD_INVALID:
+		ret = -EINVAL;
 		break;
 	}
 
-- 
2.47.3