Revert "Makefile.package.in: allow packages to override download step"

This reverts commit 48cf66f1a2e2c501abeee98b7a2268b0d6d2010d.

Signed-off-by: Maxime Petazzoni <maxime.petazzoni@bulix.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/Makefile.package.in

@@ -402,7 +402,7 @@ $(2)_TARGET_BUILD =		$$($(2)_DIR)/.stamp_built
 $(2)_TARGET_CONFIGURE =		$$($(2)_DIR)/.stamp_configured
 $(2)_TARGET_PATCH =		$$($(2)_DIR)/.stamp_patched
 $(2)_TARGET_EXTRACT =		$$($(2)_DIR)/.stamp_extracted
-$(2)_TARGET_SOURCE ?=		$$($(2)_DIR)/.stamp_downloaded
+$(2)_TARGET_SOURCE =		$$($(2)_DIR)/.stamp_downloaded
 $(2)_TARGET_UNINSTALL =		$$($(2)_DIR)/.stamp_uninstalled
 $(2)_TARGET_CLEAN =		$$($(2)_DIR)/.stamp_cleaned
 $(2)_TARGET_DIRCLEAN =		$$($(2)_DIR)/.stamp_dircleaned