[POWERPC] Add device tree fixups for the EFIKA

We make the efika device tree compliant with the defined bindings
(at least compliant enough). This is mostly done by mangling
the device_type and compatible properties, but also adding
some missing bits.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Paul Mackerras <paulus@samba.org>