linux-xlnx: Create base Zynq-7 DTSI definition

* Create the DTS fragment for general Zynq-7 Systems.

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
linux-xlnx: Add the zynq-7-base.dtsi to SRC_URI

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
linux-xlnx: Updated qemuzynq.dts to use dtsi fragment

* Refactored qemuzynq.dts

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
meta-zc702: linux-xlnx: Added DTS file

* Switched to use custom DTS instead of the one in kernel sources
* Use the zynq-7-base.dtsi for definition

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
meta-zedboard: linux-xlnx: Refactored device tree

* Changed to using zynq-7-base.dtsi
* Mirrored disabled/non-probed devices

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