dt-bindings: Another pass removing cases of 'allOf' containing a '$ref'

Another pass at removing unnecessary use of 'allOf' with a '$ref'.

json-schema versions draft7 and earlier have a weird behavior in that
any keywords combined with a '$ref' are ignored (silently). The correct
form was to put a '$ref' under an 'allOf'. This behavior is now changed
in the 2019-09 json-schema spec and '$ref' can be mixed with other
keywords.

Cc: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-By: Vinod Koul <vkoul@kernel.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Marek Behún <kabel@kernel.org>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220228213802.1639658-1-robh@kernel.org