Revert "ata: ahci-platform: add reset control support"

This reverts commit f0f56716.

According to Thierry's view,
https://www.spinics.net/lists/linux-ide/msg55357.html
some hardware-specific drivers already use their own resets,
and the common reset might make a path to occur double controls of resets.

For now, revert the commit that adds reset control support to ahci-platform,
and hold until the solution is confirmed not be affect all hardware-specific
drivers.

Fixes: f0f56716

 ("ata: ahci-platform: add reset control support")
Reported-by: Thierry Reding <thierry.reding@gmail.com>
Suggested-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Signed-off-by: Tejun Heo <tj@kernel.org>