ppc4xx: Fix bug in PCI outbound map configuration for canyonlands

PCI outbound address map configuration doesn't match the
PCI memory address range covered by appropriate TLB entry
configuration for canyonlands causing machine check
exceptions while accessing PCI memory regions. This patch
provides a fix for this issue.

Kazuaki Ichinohe observed and reported this issue while
testing display output with PCI ATI video card on canyonlands.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Stefan Roese <sr@denx.de>