auxdisplay: hd44780: Fix DT properties to include units of measurement

DT properties specifying physical properties should contain appropriate
suffices indicating the units of measurement.

Hence amend the HD44780 DT bindings to add "chars" suffixes to the
"display-height" and "display-width" properties, and update the driver
to parse them.

Fixes: dd9502a ("dt-bindings: auxdisplay: Add bindings for Hitachi HD44780")
Fixes: d47d883 ("auxdisplay: Add HD44780 Character LCD support")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/auxdisplay/hit,hd44780.txt

@@ -15,8 +15,8 @@ Required properties:
   - rs-gpios: Must contain a GPIO specifier, referring to the GPIO pin
     connected to the "RS" (Register Select) signal line of the LCD Controller's
     bus interface,
-  - display-height: Height of the display, in character cells,
-  - display-width: Width of the display, in character cells.
+  - display-height-chars: Height of the display, in character cells,
+  - display-width-chars: Width of the display, in character cells.
 
 Optional properties:
   - rw-gpios: Must contain a GPIO specifier, referring to the GPIO pin
@@ -25,7 +25,8 @@ Optional properties:
   - backlight-gpios: Must contain a GPIO specifier, referring to the GPIO pin
     used for enabling the LCD's backlight,
   - internal-buffer-width: Internal buffer width (default is 40 for displays
-    with 1 or 2 lines, and display-width for displays with more than 2 lines).
+    with 1 or 2 lines, and display-width-chars for displays with more than 2
+    lines).
 
 Example:
 
@@ -39,6 +40,6 @@ Example:
 		enable-gpios = <&hc595 4 GPIO_ACTIVE_HIGH>;
 		rs-gpios = <&hc595 5 GPIO_ACTIVE_HIGH>;
 
-		display-height = <2>;
-		display-width = <16>;
+		display-height-chars = <2>;
+		display-width-chars = <16>;
 	};

drivers/auxdisplay/hd44780.c

@@ -264,10 +264,11 @@ static int hd44780_probe(struct platform_device *pdev)
 	}
 
 	/* Required properties */
-	ret = device_property_read_u32(dev, "display-height", &lcd->height);
+	ret = device_property_read_u32(dev, "display-height-chars",
+				       &lcd->height);
 	if (ret)
 		goto fail;
-	ret = device_property_read_u32(dev, "display-width", &lcd->width);
+	ret = device_property_read_u32(dev, "display-width-chars", &lcd->width);
 	if (ret)
 		goto fail;