newlib: remove leftover file from the binary distribution

components/newlib/.gitmodules

@@ -1,4 +0,0 @@
-[submodule "newlib_xtensa-2.2.0"]
-	path = newlib_xtensa-2.2.0
-	url = ssh://git@gitlab.espressif.cn:27227/igrokhotkov/newlib_xtensa-2.2.0.git
-	ignore = dirty