chore(xilinx): reorganize timer code into common path

Reorganized timer code into common folder, updated paths in
platform.mk and Versal/Versal NET ttc timer irq in platform_def.h for
Xilinx project.

Signed-off-by: Prasad Kummari <prasad.kummari@amd.com>
Change-Id: I504727f55099decf07a208fc95254597e6e24902
6 files changed