PCI: imx6: Remove unneeded check of platform_get_resource()

When using devm_ioremap_resource(), we do not need to check the return
value of platform_get_resource(), so just remove it.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Marek Vasut <marex@denx.de>