PCI: artpec6: Add resource name comments

Add comments about the Device Tree source of resources.  No functional
change.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>

drivers/pci/host/pcie-artpec6.c

@@ -27,9 +27,9 @@
 #define to_artpec6_pcie(x)	container_of(x, struct artpec6_pcie, pp)
 
 struct artpec6_pcie {
-	struct pcie_port	pp;
-	struct regmap		*regmap;
-	void __iomem		*phy_base;
+	struct pcie_port	pp;		/* pp.dbi_base is DT dbi */
+	struct regmap		*regmap;	/* DT axis,syscon-pcie */
+	void __iomem		*phy_base;	/* DT phy */
 };
 
 /* PCIe Port Logic registers (memory-mapped) */