ppc4xx: Sequoia: Remove cpu/ppc4xx/speed.c from NAND booting

Using cpu/ppc4xx/speed.c to calculate the bus frequency is too big
for the 4k NAND boot image so define bus_frequency to 133MHz here
which is save for the refresh counter setup.

Signed-off-by: Stefan Roese <sr@denx.de>
2 files changed