V4L/DVB (4342): Fix ext_controls align on 64 bit architectures

u64 is aligned as 128bits on x86_64 architetures, requiring an special
handling to ioctls that depends on v4l2_ext_control. 
Let's fix this before ext controls go to kernel mainstream to avoid one 
more compat32 stuff.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index a62673d..b714695 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -716,7 +716,7 @@
 		__s64 value64;
 		void *reserved;
 	};
-};
+} __attribute__ ((packed));
 
 struct v4l2_ext_controls
 {