image-overlay: depend on do_image_complete

Per Yocto commit 3341f3fb, we should depend on do_image_complete
instead of do_rootfs for the initrd images.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/meta-phosphor/classes/image-overlay.bbclass b/meta-phosphor/classes/image-overlay.bbclass
index 71768a6..dbe4daf 100644
--- a/meta-phosphor/classes/image-overlay.bbclass
+++ b/meta-phosphor/classes/image-overlay.bbclass
@@ -14,7 +14,7 @@
 
 ROOTFS ?= "${DEPLOY_DIR_IMAGE}/${IMAGE_BASENAME}-${MACHINE}.${IMAGE_BASETYPE}"
 
-do_generate_flash[depends] += "${INITRD_IMAGE}:do_rootfs"
-do_generate_flash[depends] += "${PN}:do_rootfs"
+do_generate_flash[depends] += "${INITRD_IMAGE}:do_image_complete"
+do_generate_flash[depends] += "${PN}:do_image_complete"
 
 addtask generate_flash before do_build