tiny: reverse logic for DISABLE_DEV_COREDUMP

It's desirable for allnconfig and tinyconfig targets to result in the
least amount of code possible. DISABLE_DEV_COREDUMP exists as a way to
switch off DEV_COREDUMP regardless if any drivers select
WANT_DEV_COREDUMP.

This patch renames the option to ENABLE_DEV_COREDUMP and setting it to
'n' (as in allnconfig or tinyconfig) will effectively disable device
coredump.

Cc: Josh Triplett <josh@joshtriplett.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Aristeu Rozanski <arozansk@redhat.com>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>