A number of people (myself included) have pasted bad input into xmon that
it parsed as a request to dump gigabytes of memory.

Place a limit of 128kB on the dump commands.  Also remove a stale function
prototype thats been lying around.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>