zynq-7-base.dtsi: Added 'xlnx,zynq-7000' machine compatibility

* Add compatibility with the newer machine definition for newer Linux
  kernels

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
machine/zc702-zynq7: Add ZC702 support to base layer

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
machine/zedboard-zynq7: Fixed to use updated naming convention

* Added machine documentation, reference material and links

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
machine/kc702-trd-microblazeel: Added machine documentation

* Added some reference material links

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
docs: Improve documentation of Zynq and MicroBlaze boot flows

* Add BOOT.jtag to cover booting u-boot for Zynq and MicroBlaze
* Add BOOT.tftp to cover booting the kernel for Zynq and MicroBlaze
* Add BOOT.sdcard to cover booting Zynq (using BOOT.BIN)

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
README: Clean up readme

* Add some more details regarding the boot flows
* Remove references to sub-layers

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
linux-xlnx: Split MACHINE_* handler into separate include

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