dt-bindings: mfd: LMU: Add the ramp up/down property

Document the ramp-up and ramp-down property in the binding.
Removing the "sec" from the property definition as seconds is
implied.
Signed-off-by: Dan Murphy <dmurphy@ti.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

Documentation/devicetree/bindings/mfd/ti-lmu.txt

@@ -23,8 +23,14 @@ Required properties:
          0x36 for LM3633, LM3697
          0x63 for LM3695
 
-Optional property:
+Optional properties:
   - enable-gpios: A GPIO specifier for hardware enable pin.
+  - ramp-up-us: Current ramping from one brightness level to
+		the a higher brightness level.
+		Range from 2048 us - 117.44 s
+  - ramp-down-us: Current ramping from one brightness level to
+		  the a lower brightness level.
+		  Range from 2048 us - 117.44 s
 
 Required node:
   - backlight: All LMU devices have backlight child nodes.
@@ -90,7 +96,7 @@ lm3631@29 {
 
 		lcd_bl {
 			led-sources = <0 1>;
-			ramp-up-msec = <300>;
+			ramp-up-us = <300000>;
 		};
 	};
 };
@@ -152,15 +158,15 @@ lm3633@36 {
 		main {
 			label = "main_lcd";
 			led-sources = <1 2>;
-			ramp-up-msec = <500>;
-			ramp-down-msec = <500>;
+			ramp-up-us = <500000>;
+			ramp-down-us = <500000>;
 		};
 
 		front {
 			label = "front_lcd";
 			led-sources = <0>;
-			ramp-up-msec = <1000>;
-			ramp-down-msec = <0>;
+			ramp-up-us = <1000000>;
+			ramp-down-us = <0>;
 		};
 	};
 
@@ -212,8 +218,8 @@ lm3697@36 {
 
 		lcd {
 			led-sources = <0 1 2>;
-			ramp-up-msec = <200>;
-			ramp-down-msec = <200>;
+			ramp-up-us = <200000>;
+			ramp-down-us = <200000>;
 		};
 	};