Previous cleanup patches ended dropping it when sphinx-build-wrapper
were added. Also, sphinx-pre-install can also generate caches.

So, re-add it for both.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 Documentation/Makefile | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Documentation/Makefile b/Documentation/Makefile
index f764604fa1ac..65d184eab739 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -60,8 +60,10 @@ else # HAVE_SPHINX
 
 # Common documentation targets
 htmldocs mandocs infodocs texinfodocs latexdocs epubdocs xmldocs pdfdocs linkcheckdocs:
-	$(Q)@$(srctree)/tools/docs/sphinx-pre-install --version-check
-	+$(Q)$(PYTHON3) $(BUILD_WRAPPER) $@ \
+	$(Q)PYTHONPYCACHEPREFIX="$(PYTHONPYCACHEPREFIX)" \
+		$(srctree)/tools/docs/sphinx-pre-install --version-check
+	+$(Q)PYTHONPYCACHEPREFIX="$(PYTHONPYCACHEPREFIX)" \
+		$(PYTHON3) $(BUILD_WRAPPER) $@ \
 		--sphinxdirs="$(SPHINXDIRS)" $(RUSTDOC) \
 		--builddir="$(BUILDDIR)" --deny-vf=$(FONTS_CONF_DENY_VF) \
 		--theme=$(DOCS_THEME) --css=$(DOCS_CSS) --paper=$(PAPER)
-- 
2.51.0