make config: os-release output error.

Fix not show the error
"/bin/sh: /etc/os-release: No such file or directory" when the command
'make config' is run in a System without systemv.

The instruction 'make config' pre execute the syntax
"$(shell . /etc/os-release && echo $$ID)" to identified if system is a
Slackware and Opensuse.

This change prevent show the message and is send to the /dev/null

Change-Id: I7f43e281a8d9405b2519fc653de82d9b8b645fdf