video: fbdev: omapfb: simplify the return expression of dsi_init_pll_data()

Simplify the return expression.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn>
Signed-off-by: Helge Deller <deller@gmx.de>