Staging: panel: Fixed a spacing after cast coding style issue

Fixed a spacing after cast coding style issue.

Signed-off-by: Daniel H. Hemmingsen <dhh.kernel@gmail.com>
Acked-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>