PCI: rockchip-ep: Set a 64-bit BAR if requested

Ever since commit f25b5fae

 ("PCI: endpoint: Setting a BAR size > 4 GB
is invalid if 64-bit flag is not set") it has been impossible to get the
.set_bar() callback with a BAR size > 2 GB (yes, 2GB!), if the BAR was
also not requested to be configured as a 64-bit BAR.

It is however possible that an EPF driver configures a BAR as 64-bit,
even if the requested size is < 4 GB.

Respect the requested BAR configuration, just like how it is already
respected with regards to the prefetchable bit.

Link: https://lore.kernel.org/linux-pci/20240320113157.322695-8-cassel@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>