generate_medkit: Try to use full path just to be sure

generate_medkit

@@ -161,7 +161,7 @@ mkdir -p root/usr/share/updater
 	--model="\$BOARD" \
 	--board=rtunknown \
 	--out-of-root \
-	-R root \
+	-R "$(pwd)"/root \
 	--usign="\$USIGN" \
 	--batch "file://\$TURRIS_BUILD_DIR/helpers/medkit-updater-ng.lua" || true