mpc85xx: Add 4-bits eSDHC support for MPC8569E-MDS boards

Thanks to "Errata to MPC8569E PowerQUICC III Integrated Host Processor
Family Reference Manual, Rev. 0" document, which describes all eSDHC
pins, we can add 4-bits eSDHC support for MPC8569E-MDS boards.

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