MAINTAINERS: Correct Cadence PCI driver path

de80f95 ("PCI: cadence: Move all files to per-device cadence
directory") moved files of the PCI cadence drivers, but did not update the
MAINTAINERS entry.

Since then, ./scripts/get_maintainer.pl --self-test complains:

  warning: no file matches F: drivers/pci/controller/pcie-cadence*

Repair the MAINTAINERS entry.

Link: https://lore.kernel.org/r/20200221185402.4703-1-lukas.bulwahn@gmail.com
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

MAINTAINERS

@@ -12740,7 +12740,7 @@ M:	Tom Joseph <tjoseph@cadence.com>
 L:	linux-pci@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/pci/cdns,*.txt
-F:	drivers/pci/controller/pcie-cadence*
+F:	drivers/pci/controller/cadence/
 
 PCI DRIVER FOR FREESCALE LAYERSCAPE
 M:	Minghuan Lian <minghuan.Lian@nxp.com>