nubus: Fix up header split

Due to the '#ifdef __KERNEL__' being located in the wrong place, some
definitions from the kernel API were placed in the UAPI header during
the scripted header split. Fix this. Also, remove the duplicate comment
which is only relevant to the UAPI header.

Fixes: 607ca46e ("UAPI: (Scripted) Disintegrate include/linux")
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>