PCI: mobiveil: Remove unused readl and writel functions

PCI: mobiveil: Remove unused readl and writel functions

The PCIe host controller driver for Layerscape 4th generation SoC was
added in the commit 2fdfe5a58f03 ("PCI: mobiveil: Add PCIe Gen4 RC
driver for Layerscape SoCs").

At this time two static functions were introduced that appear to
currently have no users.  Since nothing is using neither of these
functions at the moment they can be safely removed.

This resolves the following build time warnings:

  drivers/pci/controller/mobiveil/pcie-layerscape-gen4.c:45:19: warning: unused function 'ls_pcie_g4_lut_readl' [-Wunused-function]
  drivers/pci/controller/mobiveil/pcie-layerscape-gen4.c:50:20: warning: unused function 'ls_pcie_g4_lut_writel' [-Wunused-function]

Link: https://lore.kernel.org/r/20210510023032.3063932-1-kw@linux.com
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>