¶ARM] Orion5x: fix cpu window mapping for 88f6183

On the 88f6183, orion5x's setup_cpu_win() fails to ever program any
mbus bridge remap registers, which causes transactions for PCI/PCIe
IO/MEM space to get sent to random mbus targets.  Adding a check for
the 6183 in orion5x_cpu_win_can_remap() is necessary and sufficient
to make PCIe wlan cards work on the 6183 reference design.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: Nicolas Pitre <nico@marvell.com>