powerpc/e5500: set non-base IVORs

Without this, we attempt to use doorbells for IPIs, and end up
branching to some bad address.  Plus, even for the exceptions
we don't implement, it's good to handle it and get a message out.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>