dt-bindings: auxdisplay: hit,hd44780: use defines for GPIO flags

Improve example DTS readability by using known defines for GPIO flags.

Cc: Andy Shevchenko <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Signed-off-by: Andy Shevchenko <[e-mail]>

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

···
         compatible = "hit,hd44780";
         display-height-chars = <2>;
         display-width-chars = <16>;
-        data-gpios = <&pcf8574 4 0>,
-                     <&pcf8574 5 0>,
-                     <&pcf8574 6 0>,
-                     <&pcf8574 7 0>;
-        enable-gpios = <&pcf8574 2 0>;
-        rs-gpios = <&pcf8574 0 0>;
-        rw-gpios = <&pcf8574 1 0>;
-        backlight-gpios = <&pcf8574 3 0>;
+        data-gpios = <&pcf8574 4 GPIO_ACTIVE_HIGH>,
+                     <&pcf8574 5 GPIO_ACTIVE_HIGH>,
+                     <&pcf8574 6 GPIO_ACTIVE_HIGH>,
+                     <&pcf8574 7 GPIO_ACTIVE_HIGH>;
+        enable-gpios = <&pcf8574 2 GPIO_ACTIVE_HIGH>;
+        rs-gpios = <&pcf8574 0 GPIO_ACTIVE_HIGH>;
+        rw-gpios = <&pcf8574 1 GPIO_ACTIVE_HIGH>;
+        backlight-gpios = <&pcf8574 3 GPIO_ACTIVE_HIGH>;
     };