Input: add MODULE_ALIAS() to hotpluggable platform modules

Since 43cc71eed1250755986da4c0f9898f9a635cb3bf, the platform modalias
is prefixed with "platform:". Add MODULE_ALIAS() to the hotpluggable
"input" platform drivers, to re-enable auto loading.

[dbrownell@users.sourceforge.net: more drivers, registration fixes]
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>