pseries: Fix and cleanup CPU initialization and reset

The current pseries machine init function iterates over the CPUs at several
points, doing various bits of initialization.  This is messy; these can
and should be merged into a single iteration doing all the necessary per
cpu initialization.  Worse, some of these initializations were setting up
state which should be set on every reset, not just at machine init time.
A few of the initializations simply weren't necessary at all.

This patch, therefore, moves those things that need to be to the
per-cpu reset handler, and combines the remainder into two loops over
the cpus (which also creates them).  The second loop is for setting up
hash table information, and will be removed in a subsequent patch also
making other fixes to the hash table setup.

This exposes a bug in our start-cpu RTAS routine (called by the guest to
start up CPUs other than CPU0) under kvm.  Previously, this function did
not make a call to ensure that it's changes to the new cpu's state were
pushed into KVM in-kernel state.  We sort-of got away with this because
some of the initializations had already placed the secondary CPUs into the
right starting state for the sorts of Linux guests we've been running.

Nonetheless the start-cpu RTAS call's behaviour was not correct and could
easily have been broken by guest changes.  This patch also fixes it.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
