dt-bindings: clock: mediatek: document clk bindings vcodecsys for Mediatek MT6765 SoC

This patch adds the binding documentation for vcodecsys.

Signed-off-by: Mars Cheng <mars.cheng@mediatek.com>
Signed-off-by: Owen Chen <owen.chen@mediatek.com>
Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
Link: https://lore.kernel.org/r/1582278742-1626-4-git-send-email-macpaul.lin@mediatek.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>