dt-bindings: clock: ti: Add clock-output-names for clockctrl

This allows us to use clock-output-names for the clockctrl instance
name instead of relying on a custom compatible or non-standard node
names.

Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Tero Kristo <kristo@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Acked-by: Rob Herring <robh@kernel.org>
Message-Id: <20220203112337.19821-2-tony@atomide.com>