ARM: 9400/1: Remove unused struct 'mod_unwind_map'

I think this has been unused since
Commit b6f21d14 ("ARM: 9204/2: module: Add all unwind tables when
load module")

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>