arm64: zynqmp: Remove clock-names from pcap node

Clock is not used in driver and also not described in binding.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/0a0fa0ba197fa4051a2c8a24e1451cefadce7517.1688992653.git.michal.simek@amd.com