ATA/IDE: fix platform driver hotplug/coldplug

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

NOTE: both ata/pata_platform.c and ide/legacy/ide_platform.c claim
to provide "the" platform_pata driver, and there's no build-time
mutual exclusion mechanism.  This means that configs which enable
both drivers will make some trouble when hotplugging...

[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>
Cc: Tejun Heo <htejun@gmail.com>
Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>