opkg-utils: use $(HOST_DIR) as PREFIX instead of DESTDIR

... and remove the /usr prefix

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/opkg-utils/opkg-utils.mk

@@ -15,7 +15,7 @@ define HOST_OPKG_UTILS_BUILD_CMDS
 endef
 
 define HOST_OPKG_UTILS_INSTALL_CMDS
-	$(MAKE) -C $(@D) DESTDIR=$(HOST_DIR) PREFIX=/usr install
+	$(MAKE) -C $(@D) PREFIX=$(HOST_DIR) install
 endef
 
 $(eval $(host-generic-package))