submodule-config: correct error reporting for invalid ignore value

As 'var' contains the whole value we get error messages that repeat
the section and key currently:

warning: Invalid parameter 'true' for config option 'submodule.submodule.plugins/hooks.ignore.ignore'

Fix this by only giving the section name in the warning.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

submodule-config.c

@@ -331,7 +331,7 @@ static int parse_config(const char *var, const char *value, void *data)
 			 strcmp(value, "all") &&
 			 strcmp(value, "none"))
 			warning("Invalid parameter '%s' for config option "
-					"'submodule.%s.ignore'", value, var);
+					"'submodule.%s.ignore'", value, name.buf);
 		else {
 			free((void *) submodule->ignore);
 			submodule->ignore = xstrdup(value);