[POWERPC] 8xx: Off-by-one fixes to SCC parameter RAM definitions

The SCC parameter RAM areas are mapped wrong in MPC8xx device descriptions. All
memory areas overlap with the next one, so that I2C, SPI, SMC1 and SMC2 cannot
be enabled if the four SCCs are.

Signed-off-by: Kalle Pokki <kalle.pokki@iki.fi>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>