board/zynq/post-image.sh: support linux 6.6 dts directory structure
Linux 6.6 includes a xilinx directory in the dts directory structure for zynq
boards. This patch updates the post-image.sh to match the zynqmp post-image.sh
in order to support this change.
Signed-off-by: Neal Frager <neal.frager@amd.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>