Prepare for additional flash banks not located at address 0
Change-Id: I60b78c917f94fa52bf24df9e3315536f776eec84
Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
Reviewed-on: http://openocd.zylin.com/4440
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>