fbdev: radeon: Clean up some inconsistent indenting

No functional modification involved.

Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=1932
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Helge Deller <deller@gmx.de>