[XEN][POWERPC] Flush the ERAT very early on secondary processors.

[XEN][POWERPC] Flush the ERAT very early on secondary processors.
This patch solves the problem with the "Synchronizing timebase hang"
that both SMP and "nosmp" users have experienced.  It blows away the
ERAT but performing an SLBIA in the seconadry processor "spinup" code.
Signed-off-by: Amos Waterland <apw@us.ibm.com>
Signed-off-by: Jimi Xenidis <jimix@watson.ibm.com>
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
--HG--
extra : transplant_source : 8%17%C8L%B7%E8%16GW%80B%D3%E7%25%94%1E%E5%F2LQ