We have stubs for most OF interfaces even when CONFIG_OF is not set, so we
allow building of pcie-mt7621.c in that case for compile testing.

When CONFIG_OF is not set, "of_match_ptr(mt7621_pcie_ids)" compiles to
NULL, which leaves mt7621_pcie_ids unused:

  $ make W=1
  drivers/pci/controller/pcie-mt7621.c:549:34: warning: unused variable 'mt7621_pcie_ids' [-Wunused-const-variable]

Drop of_match_ptr() to avoid the unused variable warning.

[bhelgaas: commit log]
Fixes: 2bdd5238 ("PCI: mt7621: Add MediaTek MT7621 PCIe host controller driver")
Link: https://lore.kernel.org/r/20220124113003.406224-2-sergio.paracuellos@gmail.com
Link: https://lore.kernel.org/r/202201241754.igtHzgHv-lkp@intel.comReported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>