arm64: zynqmp: Rename ams_ps/pl node names

Fix child node names to be aligned with commit 39dd2d1e ("dt-bindings:
iio: adc: Add Xilinx AMS binding documentation") which requires names as
ams-ps@ and ams-pl@.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/373136eccf8d22cdfb499adbc8d5f5510d6c1035.1683034376.git.michal.simek@amd.com