ARM: at91/ide: remove unsused at91-ide Kconfig entry

Commit cf844751 ("ARM: at91: drop ide driver in favor of the pata
one") removed the at91-ide driver but did not remove the Kconfig entry.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>