e <asm/unistd.h> gets included, which means we
get extra stuff that we don't need or want.

This fixes the problem by undefining __KERNEL__ once we have
included the file for which we need __KERNEL__ defined.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <19211.24287.453183.78836@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>