powerpc/64s: Include <asm/nmi.h> header file to fix a warning

[Michael Ellerman]

On Tue, 2019-03-12 at 20:18:23 UTC, Mathieu Malaterre wrote:
> Make sure to include <asm/nmi.h> to provide the following prototype:
> hv_nmi_check_nonrecoverable.
> 
> Remove the following warning treated as error (W=1):
> 
>   arch/powerpc/kernel/traps.c:393:6: error: no previous prototype for 'hv_nmi_check_nonrecoverable' [-Werror=missing-prototypes]
> 
> Signed-off-by: Mathieu Malaterre <malat at debian.org>
> Reviewed-by: Christophe Leroy <christophe.leroy at c-s.fr>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/de3c83c2fd2b87cf68214eda76dfa669

cheers