PCI: dwc: Change size to u64 for EP outbound iATU

Since outbound iATU permits size to be greater than 4GB for which the
support is also available, allow EP function to send u64 size instead of
truncating to u32.

Link: https://lore.kernel.org/r/1609929900-19082-1-git-send-email-shradha.t@samsung.com


Signed-off-by: Shradha Todi <shradha.t@samsung.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Pankaj Dubey <pankaj.dubey@samsung.com>