Fix FRV minimum slab/kmalloc alignment

> +#define	ARCH_KMALLOC_MINALIGN		(sizeof(long) * 2)
> +#define	ARCH_SLAB_MINALIGN		(sizeof(long) * 2)

This doesn't work if SLAB is selected and slab debugging is enabled as
these are passed to the preprocessor, and the preprocessor doesn't
understand sizeof.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>