powerpc/4xx: Don't unmap NULL mbase

Signed-off-by: huhai <huhai@tj.kylinos.cn>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200521072648.1254699-1-mpe@ellerman.id.au

arch/powerpc/platforms/4xx/pci.c

@@ -1242,7 +1242,7 @@ static void __init ppc460sx_pciex_check_link(struct ppc4xx_pciex_port *port)
 	if (mbase == NULL) {
 		printk(KERN_ERR "%pOF: Can't map internal config space !",
 			port->node);
-		goto done;
+		return;
 	}
 
 	while (attempt && (0 == (in_le32(mbase + PECFG_460SX_DLLSTA)
@@ -1252,9 +1252,7 @@ static void __init ppc460sx_pciex_check_link(struct ppc4xx_pciex_port *port)
 	}
 	if (attempt)
 		port->link = 1;
-done:
 	iounmap(mbase);
-
 }
 
 static struct ppc4xx_pciex_hwops ppc460sx_pcie_hwops __initdata = {