Add missing clk_disable() call to ata_host_activate() failure path.

Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Reviewed-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Tejun Heo <tj@kernel.org>