media: ccs-core.c: fix failure to call clk_disable_unprepare

Fixes smatch warning:

drivers/media/i2c/ccs/ccs-core.c:1676 ccs_power_on() warn: 'sensor->ext_clk' from clk_prepare_enable() not released on lines: 1606.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>