dt-bindings: Add LG LP097QX1-SPA1 panel binding

The LG LP097QX1-SPA1 is an 9.7", 2048x1536 (QXGA) TFT-LCD panel
connected using eDP interfaces.
Signed-off-by: Yakir Yang <ykk@rock-chips.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Documentation/devicetree/bindings/display/panel/lg,lp097qx1-spa1.txt

+LG 9.7" (2048x1536 pixels) TFT LCD panel
+
+Required properties:
+- compatible: should be "lg,lp097qx1-spa1"
+
+This binding is compatible with the simple-panel binding, which is specified
+in simple-panel.txt in this directory.