drivers/video/nvidia/nvidia.c: fix warning

Fix the int/bool confusion in there.

  drivers/video/nvidia/nvidia.c:1602: warning: return from incompatible pointer type

Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>