default.xml: add meta-fsl-ppc in the manifest file

Change-Id: I0d59dc32f1b500156d5acdeecfe1dd4a56a63c9d
Signed-off-by: Zhenhua Luo <zhenhua.luo@freescale.com>
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>