obmc-console: Fix readability-isolate-declaration

For example:

```
/usr/bin/clang-tidy -checks=-*, readability-isolate-declaration -export-fixes /tmp/tmpoo7fbs72/tmpo8xiwfxs.yaml -p=build /mnt/host/andrew/home/andrew/src/openbmc/obmc-console/test/test-client-escape.c
/mnt/host/andrew/home/andrew/src/openbmc/obmc-console/build/../config.c:61:2: error: multiple declarations in a single statement reduces readability [readability-isolate-declaration,-warnings-as-errors]
        char *name, *value;
        ^~~~~~~~~~~~~~~~~~~
/mnt/host/andrew/home/andrew/src/openbmc/obmc-console/build/../config.c:62:2: error: multiple declarations in a single statement reduces readability [readability-isolate-declaration,-warnings-as-errors]
        char *p, *line;
        ^~~~~~~~~~~~~~~
/mnt/host/andrew/home/andrew/src/openbmc/obmc-console/build/../config.c:110:2: error: multiple declarations in a single statement reduces readability [readability-isolate-declaration,-warnings-as-errors]
        size_t size, len;
        ^~~~~~~~~~~~~~~~~
/mnt/host/andrew/home/andrew/src/openbmc/obmc-console/build/../config.c:170:2: error: multiple declarations in a single statement reduces readability [readability-isolate-declaration,-warnings-as-errors]
        struct config_item *item, *next;
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/mnt/host/andrew/home/andrew/src/openbmc/obmc-console/build/../console-client.c:263:2: error: multiple declarations in a single statement reduces readability [readability-isolate-declaration,-warnings-as-errors]
        struct console_client _client, *client;
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
6 warnings generated.
```

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: Ia7829b1672ea2dfb3fa020c7c48bd8266e6a1769
diff --git a/log-handler.c b/log-handler.c
index 5b17c94..ab30827 100644
--- a/log-handler.c
+++ b/log-handler.c
@@ -130,7 +130,8 @@
 		    struct config *config)
 {
 	struct log_handler *lh = to_log_handler(handler);
-	const char *filename, *logsize_str;
+	const char *filename;
+	const char *logsize_str;
 	size_t logsize = default_logsize;
 	int rc;