powerpc/85xx: load ucode from nand flash before qe_init

In the case the QE's microcode is stored in nand flash, we need to load it from
NAND flash to ddr first then the qe_init can get the ucode correctly.

Signed-off-by: Haiying Wang <Haiying.Wang@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>