powerpc/85xx: Add STMicro M25P40 serial flash support for MPC8569E-MDS

For serial flash support we need to:

- Add QE Par IO Bank E device tree node, a GPIO from this bank is
  used for SPI chip-select line;
- Add serial-flash node;
- Add proper module alias into of/base.c.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>