PCI: imx6: Removed unused struct imx6_pcie.mem_base

Removed the unused struct imx6_pcie.mem_base member.  No functional change
intended.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/host/pci-imx6.c

@@ -48,7 +48,6 @@ struct imx6_pcie {
 	struct pcie_port	pp;
 	struct regmap		*iomuxc_gpr;
 	enum imx6_pcie_variants variant;
-	void __iomem		*mem_base;
 	u32			tx_deemph_gen1;
 	u32			tx_deemph_gen2_3p5db;
 	u32			tx_deemph_gen2_6db;