Input: s3c2410_ts - fix preparing/enabling clock

Use clk_prepare_enable/clk_disable_unprepare to make the driver
work properly with common clock framework.

Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>