arch/powerpc/platforms/powernv/setup.c: included asm/xics.h twice

arch/powerpc/platforms/powernv/setup.c: included 'asm/xics.h' twice,
remove the duplicate.

Signed-off-by: Danny Kukawka <danny.kukawka@bisect.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>