[POWERPC] EEH: rm un-needed data

The EEH event notification system passes around data that is
not needed or at least, not used properly. Stop passing this
data; get it in a more reliable fashion.

Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>