drivers: modem: ublox-sara-r4: Fix dereference before null check

Fixes #32916

Signed-off-by: Xavier Chapron <xavier.chapron@stimio.fr>

drivers/modem/ublox-sara-r4.c

@@ -314,6 +314,10 @@ static ssize_t send_socket_data(void *obj,
 	struct sockaddr *dst_addr = msg->msg_name;
 	size_t buf_len = 0;
 
+	if (!sock) {
+		return -EINVAL;
+	}
+
 	for (int i = 0; i < msg->msg_iovlen; i++) {
 		if (!msg->msg_iov[i].iov_base || msg->msg_iov[i].iov_len == 0) {
 			errno = EINVAL;
@@ -331,10 +335,6 @@ static ssize_t send_socket_data(void *obj,
 		dst_addr = &sock->dst;
 	}
 
-	if (!sock) {
-		return -EINVAL;
-	}
-
 	/*
 	 * Binary and ASCII mode allows sending MDM_MAX_DATA_LENGTH bytes to
 	 * the socket in one command