media: ad5820: DT new optional field enable-gpios

Document new enable-gpio field. It can be used to disable the part
without turning down its regulator.

Cc: devicetree@vger.kernel.org
Signed-off-by: NRicardo Ribalda Delgado <ribalda@kernel.org>
Acked-by: NPavel Machek <pavel@ucw.cz>
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/devicetree/bindings/media/i2c/ad5820.txt

@@ -8,6 +8,11 @@ Required Properties:
 
   - VANA-supply: supply of voltage for VANA pin
 
+Optional properties:
+
+   - enable-gpios : GPIO spec for the XSHUTDOWN pin. The XSHUTDOWN signal is
+active low, a high level on the pin enables the device.
+
 Example:
 
        ad5820: coil@c {
@@ -15,5 +20,6 @@ Example:
                reg = <0x0c>;
 
                VANA-supply = <&vaux4>;
+               enable-gpios = <&msmgpio 26 GPIO_ACTIVE_HIGH>;
        };