wayland: Fix DPI calculation with scaled outputs

`driverdata->width` and `driverdata->height` represent the width and height in logical pixels on scaled outputs with xdg_output. However, to correctly calculate the display's DPI value, we need to use its native resolution.

For example, on a 27" 4K screen with 175% scaling, we have `width` == 2192 and `height` == 1233, resulting in a bogus value of 92dpi, whereas 162dpi are correct for 3840x2160 pixels at 27 inches.

Tested on GNOME mutter 45.1.

src/video/wayland/SDL_waylandvideo.c

@@ -619,17 +619,17 @@ static void display_handle_done(void *data,
 
     /* Calculate the display DPI */
     if (driverdata->transform & WL_OUTPUT_TRANSFORM_90) {
-        driverdata->hdpi = driverdata->physical_height ? (((float)driverdata->height) * 25.4f / driverdata->physical_height) : 0.0f;
-        driverdata->vdpi = driverdata->physical_width ? (((float)driverdata->width) * 25.4f / driverdata->physical_width) : 0.0f;
-        driverdata->ddpi = SDL_ComputeDiagonalDPI(driverdata->height,
-                                                  driverdata->width,
+        driverdata->hdpi = driverdata->physical_height ? (((float)driverdata->native_height) * 25.4f / driverdata->physical_height) : 0.0f;
+        driverdata->vdpi = driverdata->physical_width ? (((float)driverdata->native_width) * 25.4f / driverdata->physical_width) : 0.0f;
+        driverdata->ddpi = SDL_ComputeDiagonalDPI(driverdata->native_height,
+                                                  driverdata->native_width,
                                                   ((float)driverdata->physical_height) / 25.4f,
                                                   ((float)driverdata->physical_width) / 25.4f);
     } else {
-        driverdata->hdpi = driverdata->physical_width ? (((float)driverdata->width) * 25.4f / driverdata->physical_width) : 0.0f;
-        driverdata->vdpi = driverdata->physical_height ? (((float)driverdata->height) * 25.4f / driverdata->physical_height) : 0.0f;
-        driverdata->ddpi = SDL_ComputeDiagonalDPI(driverdata->width,
-                                                  driverdata->height,
+        driverdata->hdpi = driverdata->physical_width ? (((float)driverdata->native_width) * 25.4f / driverdata->physical_width) : 0.0f;
+        driverdata->vdpi = driverdata->physical_height ? (((float)driverdata->native_height) * 25.4f / driverdata->physical_height) : 0.0f;
+        driverdata->ddpi = SDL_ComputeDiagonalDPI(driverdata->native_width,
+                                                  driverdata->native_height,
                                                   ((float)driverdata->physical_width) / 25.4f,
                                                   ((float)driverdata->physical_height) / 25.4f);
     }