[MTD] Cleanup of 'ioremap balanced with iounmap for drivers/mtd subsystem'

Updated version of patch, in response to comments from Francois Romieu
<romieu@fr.zoreil.com>

Remove gratuitous casts from iounmap and initialisation of variables.

Signed-off-by: Amol Lad <amol@verismonetworks.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

drivers/mtd/maps/nettel.c

@@ -463,7 +463,7 @@ int __init nettel_init(void)
 
 #ifdef CONFIG_MTD_CFI_INTELEXT
 out_unmap1:
-	iounmap((void *) nettel_intel_map.virt);
+	iounmap(nettel_intel_map.virt);
 #endif
 
 out_unmap2: