media: i2c: imx290: Check for availability in probe()

media: i2c: imx290: Check for availability in probe()

Currently, the V4L2 subdevice is also created when the device is not
available/connected. From userspace perspective, there is no visible
difference between a working and not-working subdevice (except when
trying it out).

This commit adds a simple preparation step, which includes an
availability check, before the subdev is initialized.

Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>