video: au1100fb: Delete an unnecessary variable initialisation in au1100fb_drv_probe()

The local variable "fbdev" will be reassigned by a following statement.
Thus omit the explicit initialisation at the beginning.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>