doc-rst: vidioc-g-edid remove a duplicate declaration

The ioctl is declared twice. This causes the following warning:
	/devel/v4l/patchwork/Documentation/linux_tv/media/v4l/vidioc-g-edid:7:
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/linux_tv/media/v4l/vidioc-g-edid.rst

@@ -19,8 +19,6 @@ Synopsis
 
 .. cpp:function:: int ioctl( int fd, int request, struct v4l2_edid *argp )
 
-.. cpp:function:: int ioctl( int fd, int request, struct v4l2_edid *argp )
-
 Arguments
 =========