ioremap balanced with iounmap for drivers/mtd subsystem

ioremap must be balanced by an iounmap and failing to do so can result
in a memory leak.

Tested (compilation only) with:
- allmodconfig
- Modifying drivers/mtd/maps/Kconfig and drivers/mtd/nand/Kconfig to
make sure that the changed file is compiling without warning

Signed-off-by: Amol Lad <amol@verismonetworks.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
diff --git a/drivers/mtd/maps/pcmciamtd.c b/drivers/mtd/maps/pcmciamtd.c
index c861134..995347b 100644
--- a/drivers/mtd/maps/pcmciamtd.c
+++ b/drivers/mtd/maps/pcmciamtd.c
@@ -602,6 +602,10 @@
 	ret = pcmcia_request_configuration(link, &link->conf);
 	if(ret != CS_SUCCESS) {
 		cs_error(link, RequestConfiguration, ret);
+		if (dev->win_base) {
+			iounmap(dev->win_base);
+			dev->win_base = NULL;
+		}
 		return -ENODEV;
 	}