dt-bindings: Add support for samsung s6e3hf2 panel

The samsung s6e3hf2 panel is a 5.65" 1600x2560 AMOLED panel connected
using MIPI-DSI interfaces.

The s6e3hf2 is add to samsung,s6e3ha2.txt binding because it is a
panel similar to the s6e3ha2. So add the compatible string and
comments.
Signed-off-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1492504836-19225-2-git-send-email-hoegeun.kwon@samsung.com

Documentation/devicetree/bindings/display/panel/samsung,s6e3ha2.txt

 Samsung S6E3HA2 5.7" 1440x2560 AMOLED panel
+Samsung S6E3HF2 5.65" 1600x2560 AMOLED panel
 
 Required properties:
-  - compatible: "samsung,s6e3ha2"
+  - compatible: should be one of:
+    "samsung,s6e3ha2",
+    "samsung,s6e3hf2".
   - reg: the virtual channel number of a DSI peripheral
   - vdd3-supply: I/O voltage supply
   - vci-supply: voltage supply for analog circuits