powerpc/85xx: Use fsl,mpc85.. as prefix for memory ctrl & l2-cache nodes

Older devices tree's used "fsl,85.." instead of the preferred
"fsl,mpc85.." for the memory controller & l2 cache controller nodes.
The EDAC code is the only use of these and has been updated for some
time to support both "fsl,85.." and "fsl,mpc85.."

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>