docs/build-yocto-udooneo: Fix build script
docs/build-yocto-udooneo: Fix build script

bitbake m4-firmware before bitbaking the actual image.

Workaround for issue https://github.com/gmacario/easy-jenkins/issues/57

Signed-off-by: Gianpaolo Macario <f8885408b8c3d931b330bae3c3a28a3af912c463@gmail.com>
gmacario/easy-jenkins