[PATCH] powerpc: Remove stale iseries global

Not even the iSeries maintainer seems to have access to this legendary
piranha simulator. It adds a bit of ugliness in the common time init
code, and if it's no longer used we might as well be done with it and
remove the bloat.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>