doc_rst: rename the media Sphinx suff to Documentation/media

The name of the subsystem is "media", and not "linux_tv". Also,
as we plan to add other stuff there in the future, let's
rename also the media uAPI book to media_uapi, to make it
clearer.

No functional changes.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
diff --git a/Documentation/Makefile.sphinx b/Documentation/Makefile.sphinx
index 5aa2161..4c87a41 100644
--- a/Documentation/Makefile.sphinx
+++ b/Documentation/Makefile.sphinx
@@ -35,7 +35,7 @@
       cmd_sphinx = BUILDDIR=$(BUILDDIR) $(SPHINXBUILD) -b $2 $(ALLSPHINXOPTS) $(BUILDDIR)/$2
 
 htmldocs:
-	$(MAKE) BUILDDIR=$(BUILDDIR) -f $(srctree)/Documentation/linux_tv/Makefile $@
+	$(MAKE) BUILDDIR=$(BUILDDIR) -f $(srctree)/Documentation/media/Makefile $@
 	$(call cmd,sphinx,html)
 
 pdfdocs: