PPC: E500: Set ESR values

When an exception occurs on BookE, we need to set ESR bits to expose
to the guest information on what exactly happened. Add the obvious ones.

Reported-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>