ARM: zynq: Clean DTSI coding style

Fix minor indentation problems.

Signed-off-by: Michal Simek <monstr@monstr.eu>
Reviewed-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Reviewed-by: Moritz Fischer <moritz.fischer@ettus.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>