[POWERPC] lite5200(b) DTS fixes

Three trivial DTS fixes:
 -Mark Lite5200(b) boards as "mpc5200" compatible. On efika the
  firmware already does that.
 -Fix mscan interrupt.
 -Fix wakeup GPIO address.

Signed-off-by: Domen Puncer <domen.puncer@telargo.com>
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>