This patch corrects small mistake in the register list in
doc/README.mpc8536ds. These registers are 32 bits and this one starts
at ....c not ....e

When using the ...c address I can boot from sd, when using the ...e
address I cannot.

Signed-off-by: Frans Meulenbroeks <fransmeulenbroeks@gmail.com>
Acked-by: Hu Mingkai <B21284@freescale.com>