dt-bindings: clock: Add NPU clock controller device bindings for KONA

Add binding documentation for the KONA NPU clock controller.
Also update the npucc header file to remove the npu_cc_aon_clk
which should not be modified by software.

Change-Id: I5002cc61c81fb696fc69c438a2d71cba28e61f16
Signed-off-by: David Collins <collinsd@codeaurora.org>