misc: xilinx_trafgen: deprecate the driver

commit 9d3dd213550025f0109dafbaf573c64d282c8092 from
https://github.com/Xilinx/linux-xlnx.git

 xlnx_rebase_v5.15

There are not many users for the driver.
Deprecate the driver.

Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
State: pending
Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com>