xhci: translate virtual addresses into the bus's address space

So far we've been content with passing physical addresses when
configuring memory addresses into XHCI controllers, but not all
platforms have buses with transparent mappings. Specifically the
Raspberry Pi 4 might introduce an offset to memory accesses incoming
from its PCIe port.

Introduce xhci_virt_to_bus() and xhci_bus_to_virt() to cater with these
limitations, and make sure we don't break non DM users.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-by: Peter Robinson <pbrobinson@gmail.com>
[mb: fix compilation for 32 bit]
Signed-off-by: Matthias Brugger <mbrugger@suse.com>

fix from nicolas