drm: Use of_property_read_bool() for boolean properties

It is preferred to use typed property access functions (i.e.
of_property_read_<type> functions) rather than low-level
of_get_property/of_find_property functions for reading properties.
Convert reading boolean properties to of_property_read_bool().

Reviewed-by: Laurent Pinchart <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Rob Herring <[e-mail]>

drivers/gpu/drm/bridge/parade-ps8622.c

···
 		ps8622->lane_count = ps8622->max_lane_count;
 	}
 
-	if (!of_find_property(dev->of_node, "use-external-pwm", NULL)) {
+	if (!of_property_read_bool(dev->of_node, "use-external-pwm")) {
 		ps8622->bl = backlight_device_register("ps8622-backlight",
 				dev, ps8622, &ps8622_backlight_ops,
 				NULL);

drivers/gpu/drm/tiny/ofdrm.c

···
 	bool big_endian;
 
 #ifdef __BIG_ENDIAN
-	big_endian = true;
-	if (of_get_property(of_node, "little-endian", NULL))
-		big_endian = false;
+	big_endian = !of_property_read_bool(of_node, "little-endian");
 #else
-	big_endian = false;
-	if (of_get_property(of_node, "big-endian", NULL))
-		big_endian = true;
+	big_endian = of_property_read_bool(of_node, "big-endian");
 #endif
 
 	return big_endian;