Staging: panel: Fix space prohibited between function name and open paranthesis

This patch fixes the following checkpatch.pl issues in panel.c:
WARNING: space prohibited between function name and open parenthesis '('

Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>