include/linux: remove empty conditionals

Commit 607ca46e ("UAPI: (Scripted) Disintegrate include/linux") left
behind some empty conditional blocks.  Since they are useless and may
cause a reader to wonder whether something is missing, remove them.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>