PCI: designware: Wait for link to come up with consistent style

All the DesignWare-based host drivers loop waiting for the link to come up,
but they do it several ways that are needlessly different.

Wait for the link to come up in a consistent style across all the
DesignWare drivers.  No functional change.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Pratyush Anand <pratyush.anand@gmail.com>