arm64: zynqmp: Add psgtr DT descriptions

Mainline kernel has psgtr driver that's why it is good to add description
to DT files. Some boards are just missing description for USB3 and sata.
zc1751-dc1 and p-a2197 are also missing clock descriptions for input
clocks.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>