tune-microblaze: Add negative CCARGS definitions

* Add args to turn off CPU features

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
meta-kc705: kc705-trd: Update configuration to match exact hardware

* Update configuration files and DTS to match the exact Targeted Reference
  Design configuration.

Signed-off-by: Nathan Rossi <nathan.rossi@xilinx.com>
linux-xlnx: Fix DEPENDS for microblaze targets

* Fix the DEPENDS for microblaze, use '_append' instead of just '+='.

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