Input: export input_reset_device() for use in KGDB

KGDB, much like the resume process, needs to be able to mark all keys that
were pressed at the time we dropped into the debuggers as "released", since
it is unlikely that the keys stay pressed for the entire duration of the
debug session.

Also we need to make sure that input_reset_device() and input_dev_suspend()
only attempt to change state of currenlt opened devices since closed devices
may not be ready to accept IO requests.

Tested-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>