Documentation/sphinx: fix make SPHINXDIRS="dirs" pdfdocs for more than one dir

Add missing semicolon to fix pdf build with more than one SPHINXDIRS
directory specified. For example make SPHINXDIRS="gpu media" pdfdocs.

Fixes: cd21379b16 ("doc-rst: generic way to build PDF of sub-folders")
Signed-off-by: Markus Heiser <markus.heiser@darmarIT.de>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Documentation/Makefile.sphinx

@@ -80,7 +80,7 @@ pdfdocs:
 else # HAVE_PDFLATEX
 
 pdfdocs: latexdocs
-	$(foreach var,$(SPHINXDIRS), $(MAKE) PDFLATEX=$(PDFLATEX) LATEXOPTS="$(LATEXOPTS)" -C $(BUILDDIR)/$(var)/latex)
+	$(foreach var,$(SPHINXDIRS), $(MAKE) PDFLATEX=$(PDFLATEX) LATEXOPTS="$(LATEXOPTS)" -C $(BUILDDIR)/$(var)/latex;)
 
 endif # HAVE_PDFLATEX