media: imx: remove code for non-existing config IMX_GPT_ICAP

There never was a config IMX_GPT_ICAP in the repository. So remove the code
conditional on this config and simplify the callers that just called empty
functions.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Tommaso Merciai <tommaso.merciai@amarulasolutions.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>