PCI specification allow prefetchable memory to be 32-bit or 64-bit.
PCI express specification states that all memmory bars for prefetchable
memory must be implemented as 64-bit. They all require that 64 bit
prefetchble memory are suported especially when u-boot is ported to
more and more 64bit processors.
Signed-off-by: David Feng <fenghua@phytium.com.cn>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
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