PCI: layerscape: Remove redundant error message from ls_pcie_probe()

There is an error message from devm_ioremap_resource() already, so remove
the dev_err() call to avoid redundant error messages.

Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>