media: atomisp: Replace open-coded i2c_find_device_by_fwnode()

gmin_i2c_dev_exists() is using open-coded variant of
i2c_find_device_by_fwnode(). Replace it with a corresponding call.

Link: https://lore.kernel.org/r/20240326202813.1425431-3-andriy.shevchenko@linux.intel.com



Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>