pci-host: Delegate bswap to mmio layer

pci-host: Delegate bswap to mmio layer

The only reason we have bswap versions of the pci host code is that
most pci host devices are little endian. The ppc e500 is the only
odd one here, being big endian.

So let's directly pass the endianness down to the mmio layer and not
worry about it on the pci host layer.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>