dt-bindings: imx-ocotp: add compatible string for i.MX7D/S

Add compatible string for i.MX7D/S

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>