arm: mvebu: Move PCI(e) MBUS window to end of RAM

arm: mvebu: Move PCI(e) MBUS window to end of RAM

With patch 49b23e035d96 (pci: mvebu: Increase size of PCIe default mapping)
the mapping size for each PCI(e) controller was increased from 32MiB to
128MiB. This leads to problems on boards with multiple PCIe slots / ports
which are unable to map all PCIe ports, e.g. the Armada-XP theadorable:

DRAM:  2 GiB (667 MHz, 64-bit, ECC not enabled)
SF: Detected m25p128 with page size 256 Bytes, erase size 256 KiB, total 16 MiB
Cannot add window '4:f8', conflicts with another window
PCIe unable to add mbus window for mem at f0000000+08000000
Model: Marvell Armada XP theadorable

This patch moves the base address for the PCI(e) memory spaces from
0xe8000000 to the end of SDRAM (clipped to a max of 0xc0000000 right now).
This gives move room and flexibility for PCI(e) mappings.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: VlaoMao <vlaomao@gmail.com>
Tested-by: VlaoMao <vlaomao at gmail.com>