dt-bindings: usb: Convert jz4740-musb doc to YAML

Convert ingenic,jz4740-musb.txt to ingenic,musb.yaml, and add the
new ingenic,jz4770-musb and ingenic,jz4725b-musb compatible strings
in the process.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bin Liu <b-liu@ti.com>
Link: https://lore.kernel.org/r/20200316211136.2274-3-b-liu@ti.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>