media: ov6650: Fix control handler not freed on init error

Since commit afd9690c ("[media] ov6650: convert to the control
framework"), if an error occurs during initialization of a control
handler, resources possibly allocated to the handler are not freed
before device initialiaton is aborted.  Fix it.

Fixes: afd9690c ("[media] ov6650: convert to the control framework")
Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>