dt-bindings: Fix JSON pointers

dt-bindings: Fix JSON pointers

The correct syntax for JSON pointers begins with a '/' after the '#'.
Without a '/', the string should be interpreted as a subschema
identifier. The jsonschema module currently doesn't handle subschema
identifiers and incorrectly allows JSON pointers to begin without a '/'.
Let's fix this before it becomes a problem when jsonschema module is
fixed.

Converted with:
perl -p -i -e 's/yaml#definitions/yaml#\/definitions/g' `find Documentation/devicetree/bindings/ -name "*.yaml"`

Cc: Maxime Ripard <mripard@kernel.org>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jingoo Han <jingoohan1@gmail.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: netdev@vger.kernel.org
Acked-By: Vinod Koul <vkoul@kernel.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Sebastian Reichel <sre@kernel.org>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20201217223429.354283-1-robh@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>