leds: trigger: remove reference to obsolete CONFIG_IDE_GD_ATA

Commit b7fb14d3 ("ide: remove the legacy ide driver") removes the
definition of the config IDE_GD_ATA.

So, remove the obsolete reference in ./drivers/leds/trigger/Kconfig.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>