powerpc: Inline ppc64_runlatch_off

I'm sick of seeing ppc64_runlatch_off in our profiles, so inline it
into the callers. To avoid a mess of circular includes I didn't add
it as an inline function.

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>