pci: imx: Adjust the return value when imx_pcie_addr_valid() fails

When trying to access non-existent/unsupported PCI devices in
imx_pcie_read_config(), when imx_pcie_addr_valid() fails it returns
error code and fills in the result with 0xffffffff manually. But it
really should return zero to upper layer codes.

Reported-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Fabio Estevam <fabio.estevam@nxp.com>
diff --git a/drivers/pci/pcie_imx.c b/drivers/pci/pcie_imx.c
index f1e189e..c14bb0a 100644
--- a/drivers/pci/pcie_imx.c
+++ b/drivers/pci/pcie_imx.c
@@ -381,7 +381,7 @@
 	ret = imx_pcie_addr_valid(d);
 	if (ret) {
 		*val = 0xffffffff;
-		return ret;
+		return 0;
 	}
 
 	va_address = get_bus_address(d, where);