dt-bindings: Add resets to the PL011 bindings

Some PL011 implementations provide a reset line to the silicon
IP block, add a device tree property for this.

Cc: devicetree@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20211120011418.2630449-1-linus.walleij@linaro.org


Signed-off-by: Rob Herring <robh@kernel.org>