Do not use UIScreenMode to add a iOS display, always use the boundary

This solves the problem that on iPad you would get 1024x768 instead
of 768x1024 when calling SDL_GetDesktopDisplayMode(0, &mode)
See Apple's doc for UIScreenMode where is says:
"Most developers should never need to use the information provided
 by this class and should simply use the bounds provided by the
 UIScreen object for their drawing space."

src/video/uikit/SDL_uikitvideo.m

@@ -199,23 +199,25 @@ UIKit_VideoInit(_THIS)
     if ([currSysVer compare:reqSysVer options:NSNumericSearch] != NSOrderedAscending)
         SDL_UIKit_supports_multiple_displays = YES;
 
-    // If this is iPhoneOS < 3.2, all devices are one screen, 320x480 pixels.
-    //  The iPad added both a larger main screen and the ability to use
-    //  external displays.
-    if (!SDL_UIKit_supports_multiple_displays) {
-        // Just give 'em the whole main screen.
+    // Add the main screen.
     UIScreen *uiscreen = [UIScreen mainScreen];
     UIScreenMode *uiscreenmode = [uiscreen currentMode];
     const CGSize size = [uiscreen bounds].size;
     UIKit_AddDisplay(uiscreen, uiscreenmode, (int)size.width, (int)size.height);
-    } else {
+
+    // If this is iPhoneOS < 3.2, all devices are one screen, 320x480 pixels.
+    //  The iPad added both a larger main screen and the ability to use
+    //  external displays. So, add the other displays (screens in UI speak).
+    if (SDL_UIKit_supports_multiple_displays) {
         for (UIScreen *uiscreen in [UIScreen screens]) {
-            // the main screen is the first element in the array.
+            // Only add the other screens
+            if (uiscreen != [UIScreen mainScreen]) {
                 UIScreenMode *uiscreenmode = [uiscreen currentMode];
-            const CGSize size = [[uiscreen currentMode] size];
+                const CGSize size = [uiscreen bounds].size;
                 UIKit_AddDisplay(uiscreen, uiscreenmode, (int)size.width, (int)size.height);
             }
         }
+    }
 
     /* We're done! */
     return 0;