dt-bindings: clock: Add binding documentation for TI Audio REFCLK

Add DT bindings for TI's audio reference clocks (REFCLK) present on AM62
SoC.

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Jai Luthra <j-luthra@ti.com>
Link: https://lore.kernel.org/r/20230515-refclk-v3-1-37c0b550f406@ti.com


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