plat: xilinx: zynqmp: Move zynqmp_def.h to include directory

Move zynqmp_def.h to platform specific include directory.
Also, update source file to include header file from updated
path of zynqmp_def.h

Signed-off-by: Tejas Patel <tejas.patel@xilinx.com>
Reviewed-by: Siva Durga Prasad Paladugu <siva.durga.paladugu@xilinx.com>
Signed-off-by: Jolly Shah <jollys@xilinx.com>