[POWERPC] EEH recovery tweaks

If one attempts to create a device driver recovery sequence that
does not depend on a hard reset of the device, but simply just
attempts to resume processing, then one discovers that the
recovery sequence implemented on powerpc is not quite right.
This patch fixes this up.

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