dt-bindings: adv7511: Extend bindings to allow specifying slave map addresses

The ADV7511 has four 256-byte maps that can be accessed via the main I2C
ports. Each map has it own I2C address and acts as a standard slave
device on the I2C bus.

Extend the device tree node bindings to be able to override the default
addresses so that address conflicts with other devices on the same bus
may be resolved at the board description level.

Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1518544137-2742-3-git-send-email-kbingham@kernel.org