PCI: designware: Move link wait definitions to .c file

Move the link wait sleep definitions to the .c file as suggested by
Jisheng Zhang in a previous patch.

Signed-off-by: Joao Pinto <jpinto@synopsys.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Jisheng Zhang <jszhang@marvell.com>