PCI: dwc: Use dev_info for PCIe link down event logging

Some of the platforms (like Tegra194 and Tegra234) have open slots and
not having an endpoint connected to the slot is not an error.
So, changing the macro from dev_err to dev_info to log the event.

Link: https://lore.kernel.org/r/20220913101237.4337-1-vidyas@nvidia.com


Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>