Input: gameport - fix attach driver code

upstream commit: 4ced8e7c

The commit 6902c0be that moved
driver registration out of kgameportd thread was incomplete and
did not add the code necessary to actually attach driver to
already registered devices, rectify that.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>