powerpc: Add __SANE_USERSPACE_TYPES__ to asm/types.h for LL64

PPC64 uses long long for u64 in the kernel, but powerpc's asm/types.h
prevents 64-bit userland from seeing this definition, instead defaulting
to u64 == long in userspace.  Some user programs (e.g. kvmtool) may actually
want LL64, so this patch adds a check for __SANE_USERSPACE_TYPES__ so that,
if defined, int-ll64.h is included instead.

Signed-off-by: Matt Evans <matt@ozlabs.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>