dt-bindings: display: msm/dsi: Add compatible for 14nm DSI PHY

Add the compatible string for 14nm DSI PHY (used in MSM8996/APQ8096).
>From 14nm PHY onwards, the "dsi_phy_regulator" reg-name is not required,
but "dsi_phy_lane" reg-name is. Update the doc to specify the reg-names
each PHY revision needs.

Cc: Rob Herring <robh@kernel.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

Documentation/devicetree/bindings/display/msm/dsi.txt

@@ -86,12 +86,19 @@ Required properties:
   * "qcom,dsi-phy-28nm-lp"
   * "qcom,dsi-phy-20nm"
   * "qcom,dsi-phy-28nm-8960"
-- reg: Physical base address and length of the registers of PLL, PHY and PHY
-  regulator
+  * "qcom,dsi-phy-14nm"
+- reg: Physical base address and length of the registers of PLL, PHY. Some
+  revisions require the PHY regulator base address, whereas others require the
+  PHY lane base address. See below for each PHY revision.
 - reg-names: The names of register regions. The following regions are required:
+  For DSI 28nm HPM/LP/8960 PHYs and 20nm PHY:
   * "dsi_pll"
   * "dsi_phy"
   * "dsi_phy_regulator"
+  For DSI 14nm PHY:
+  * "dsi_pll"
+  * "dsi_phy"
+  * "dsi_phy_lane"
 - clock-cells: Must be 1. The DSI PHY block acts as a clock provider, creating
   2 clocks: A byte clock (index 0), and a pixel clock (index 1).
 - power-domains: Should be <&mmcc MDSS_GDSC>.
@@ -102,6 +109,8 @@ Required properties:
 - vddio-supply: phandle to vdd-io regulator device node
   For 20nm PHY:
 - vddio-supply: phandle to vdd-io regulator device node
+- vcca-supply: phandle to vcca regulator device node
+  For 14nm PHY:
 - vcca-supply: phandle to vcca regulator device node
 
 Optional properties: