doc-rst: linux_tv: use :cpp:function:: on all syscalls

Now that we have one syscall per page, using :cpp:function::
cleans up almost all warnings, with is a great thing.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
diff --git a/Documentation/linux_tv/media/dvb/video-get-navi.rst b/Documentation/linux_tv/media/dvb/video-get-navi.rst
index ccb2552..6c3034f 100644
--- a/Documentation/linux_tv/media/dvb/video-get-navi.rst
+++ b/Documentation/linux_tv/media/dvb/video-get-navi.rst
@@ -15,7 +15,7 @@
 Synopsis
 --------
 
-.. c:function:: int ioctl(fd, int request = VIDEO_GET_NAVI , video_navi_pack_t *navipack)
+.. cpp:function:: int ioctl(fd, int request = VIDEO_GET_NAVI , video_navi_pack_t *navipack)
 
 
 Arguments