Change nvidiafb_remove to __devexit to fix MODPOST warnings:

WARNING: drivers/video/nvidia/nvidiafb.o - Section mismatch: reference to
.exit.text:nvidiafb_remove from .data.rel.local after 'nvidiafb_driver' (at
offset 0x28)
Signed-off-by: NPrarit Bhargava <prarit@redhat.com>
Acked-By: NJames Simmons <jsimmons@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>