[POWERPC] Restore 'proper' link order in platform

The 52xx was put before CHRP to allow EFIKA to be recognized
properly. Now the efika tree is fixed up in prom_init so
no need for this ugly hack. So we restore the 'normal'
order.

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