arm64: zynqmp: Correct psgtr description for zcu100-revC

Enable psgtr node and also fix clock names to be aligned with other zynqmp
boards.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/bd35fdaac08208578b2bb5059ba2c59bb4e66dac.1623684253.git.michal.simek@xilinx.com