drm/nouveau: fix for disabled fbdev emulation

drm/nouveau: fix for disabled fbdev emulation

Hello,

after this commit:

commit f045f459d925138fe7d6193a8c86406bda7e49da
Author: Ben Skeggs <[email protected]>
Date:   Thu Jun 2 12:23:31 2016 +1000
    drm/nouveau/fbcon: fix out-of-bounds memory accesses

kernel started to oops when loading nouveau module when using GTX 780 Ti
video adapter. This patch fixes the problem.

Bug report: https://bugzilla.kernel.org/show_bug.cgi?id=120591

Signed-off-by: Dmitrii Tcvetkov <[email protected]>
Suggested-by: Ilia Mirkin <[email protected]>
Fixes: f045f459d925 ("nouveau_fbcon_init()")
Signed-off-by: Ben Skeggs <[email protected]>
Cc: [email protected]