video: au1100fb: Move a variable assignment behind a null pointer check in au1100fb_setmode()

[Markus Elfring]

> No crash or anything can or will happen here.
>
> Markus, maybe you missed the "&" in front of "&fbdev->info" ?
Would you get into the mood to adjust development views
if you would take any feedback and further background information
(by David Svoboda for example) better into account?
https://wiki.sei.cmu.edu/confluence/display/c/EXP34-C.+Do+not+dereference+null+pointers?focusedCommentId=405504139#comment-405504139

Regards,
Markus