[PATCH] drivers/isdn: ioremap balanced with iounmap

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

Signed-off-by: Amol Lad <amol@verismonetworks.com>
Acked-by: Karsten Keil <kkeil@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>