media: atomisp: Add atomisp_register_sensor_no_gmin() helper

The DSDT of all Windows BYT / CHT devices which I have seen has proper
ACPI powermagement for the clk and regulators used by the sensors.

So there is no need for the whole custom atomisp_gmin custom code to
disable the ACPI pm and directly poke at the PMIC for this.

Add new atomisp_register_sensor_no_gmin() + atomisp_unregister_subdev()
helpers which allow registering a sensor with the atomisp code without
using any of the atomisp_gmin power-management code.

Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>