wwan: core: Pass string literal as format argument of dev_set_name()

Both gcc-14 and clang-18 report that passing a non-string literal as the
format argument of dev_set_name() is potentially insecure.

E.g. clang-18 says:

drivers/net/wwan/wwan_core.c:442:34: warning: format string is not a string literal (potentially insecure) [-Wformat-security]
  442 |         return dev_set_name(&port->dev, buf);
      |                                         ^~~
drivers/net/wwan/wwan_core.c:442:34: note: treat the string as an argument to avoid this
  442 |         return dev_set_name(&port->dev, buf);
      |                                         ^
      |                                         "%s",

It is always the case where the contents of mod is safe to pass as the
format argument. That is, in my understanding, it never contains any
format escape sequences.

But, it seems better to be safe than sorry. And, as a bonus, compiler
output becomes less verbose by addressing this issue as suggested by
clang-18.

Compile tested only.
No functional change intended.

Signed-off-by: Simon Horman <horms@kernel.org>
Acked-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Link: https://patch.msgid.link/20241023-wwan-fmt-v1-1-521b39968639@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/wwan/wwan_core.c

@@ -431,7 +431,7 @@ static int __wwan_port_dev_assign_name(struct wwan_port *port, const char *fmt)
 		return -ENFILE;
 	}
 
-	return dev_set_name(&port->dev, buf);
+	return dev_set_name(&port->dev, "%s", buf);
 }
 
 struct wwan_port *wwan_create_port(struct device *parent,