[AVFoundation] Fix typo in attribute name and add missing availability attributes. (#13548)

src/avfoundation.cs

@@ -9901,12 +9901,13 @@ namespace AVFoundation {
 		[Wrap ("Array.ConvertAll (_GetAvailableEmbeddedThumbnailPhotoCodecTypes, s => AVVideoCodecTypeExtensions.GetValue (s))", IsVirtual = true)]
 		AVVideoCodecType[] AvailableEmbeddedThumbnailPhotoCodecTypes { get; }
 
-#if XAMCORE_4_0
+#if NET
 		[iOS (11, 0)]
 		[NullAllowed, Export ("embeddedThumbnailPhotoFormat", ArgumentSemantic.Copy)]
 		NSDictionary WeakEmbeddedThumbnailPhotoFormat { get; set; }
 
-		[Warp ("WeakEmbeddedThumbnailPhotoFormat")]
+		[iOS (11, 0)]
+		[Wrap ("WeakEmbeddedThumbnailPhotoFormat")]
 		AVCapturePhotoSettingsThumbnailFormat EmbeddedThumbnailPhotoFormat { get; set; }
 #else
 		[iOS (11, 0)]