conf/machine: Create qemumicroblaze and qemuzynq machines

* qemumicroblaze = 'petalogix-ml605' QEMU machine model
* qemuzynq = 'xilinx-zynq-a9' QEMU machine model
* Added kernel configuration and DTS for machines

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
libffi: Remove outdated, mis-matched against oe-core version

* Remove obsolete recipe
* oe-core has v3.0.13

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
util-linux: Update to match oe-core version

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>