PCI: imx6: Remove redundant "Link never came up" message

When a PCI card is not connected, the following messages are seen on mx6:

  imx6q-pcie 1ffc000.pcie: phy link never came up
  imx6q-pcie 1ffc000.pcie: Link never came up

The first one comes from the pcie-designware.c core file, so remove
the redundant one from the imx6 driver.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>