[media] exynos-gsc: Clean up file handle in open() error path

The file handle is not yet added in the vfd list. So no need
to call v4l2_fh_del(&ctx->fh) if it fails to create controls.

Signed-off-by: Shailendra Verma <shailendra.v@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>