[PATCH] powerpc: EOI and clear IPI fix in xics_teardown_cpu()

If OK, please sent this patch to upstream.

Thanks
Haren

When invoked kdump boot, plpar_eoi() call is getting failed and calling 
panic().
Kernel panic - not syncing: bad return code EOI - rc = -4, value=ff000000

The issue is with the desc->chip->eoi(XICS_IPI) in xics_teardown_cpu(). 
Instead of passing the virq to desc->chip->eoi(), XICS_IPI is used. 
Also, clear IPI in xics_teardown_cpu() got removed recently (in 
2.6.17-git25).  Noticed in some crash dump cases (Ex: initiate kdump 
boot using soft-reset and xmon is enabled), IPI is not cleared for some 
CPU(s) before starting the kdump boot. Hence, causing the kdump boot 
failure.

Signed-off-by: Haren Myneni <haren@us.ibm.com>