dt-bindings: ufs: Add #reset-cells for Qualcomm controllers

Enable Qualcomm UFS controllers to expose the PHY reset via a reset
controller.
Signed-off-by: Evan Green <evgreen@chromium.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt

@@ -50,6 +50,8 @@ Optional properties:
 -lanes-per-direction	: number of lanes available per direction - either 1 or 2.
 			  Note that it is assume same number of lanes is used both
 			  directions at once. If not specified, default is 2 lanes per direction.
+- #reset-cells		: Must be <1> for Qualcomm UFS controllers that expose
+			  PHY reset from the UFS controller.
 - resets            : reset node register
 - reset-names       : describe reset node register, the "rst" corresponds to reset the whole UFS IP.
 
@@ -79,4 +81,5 @@ Example:
 		reset-names = "rst";
 		phys = <&ufsphy1>;
 		phy-names = "ufsphy";
+		#reset-cells = <1>;
 	};