powerpc/pseries: Fix kexec on recent firmware versions

powerpc/pseries: Fix kexec on recent firmware versions

commit b1301797f30370c430244979671978fc232f4533 upstream.

Recent versions of firmware will fail to unmap the virtual processor
area if we have a dispatch trace log registered. This causes kexec
to fail.

If a trace log is registered this patch unregisters it before the
SLB shadow and virtual processor areas, fixing the problem.

The address argument is ignored by firmware on unregister so we
may as well remove it.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>