Documentation/sphinx: build the media intermediate rst files for all outputs

This is a stopgap measure to allow building outputs other than html.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Acked-by: Markus Heiser <markus.heiser@darmarit.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/media/Makefile b/Documentation/media/Makefile
index 39e2d76..a7fb352 100644
--- a/Documentation/media/Makefile
+++ b/Documentation/media/Makefile
@@ -10,7 +10,8 @@
 
 TARGETS := $(addprefix $(BUILDDIR)/, $(FILES))
 
-htmldocs: $(BUILDDIR) ${TARGETS}
+.PHONY: all
+all: $(BUILDDIR) ${TARGETS}
 
 $(BUILDDIR):
 	$(Q)mkdir -p $@