dynamic_debug: deprecate ddebug_query, suggest dyndbg instead

With ddebug_dyndbg_boot_params_cb() handling bare dyndbg params, we
dont need ddebug_query param anymore.  Add a warning when processing
ddebug_query= param that it is deprecated, and to change it to dyndbg=

Add a deprecation notice for v3.8 to feature-removal-schedule.txt, and
add a suggested deprecation period of 3 releases to the header.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Acked-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>