util/format: remove left-over util_format_description_table declaration

Fixes: 3c45c4bc44 ("util: Cope with the fact that formats in u_format.csv are not ordered.")
Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/util/format/u_format.h

@@ -425,10 +425,6 @@ struct util_format_description
 };
 
 
-extern const struct util_format_description 
-util_format_description_table[];
-
-
 const struct util_format_description *
 util_format_description(enum pipe_format format);