dt-bindings: imx-ocotp: Add i.MX8MM compatible

Add compatible for i.MX8MM as per arch/arm64/boot/dts/freescale/imx8mm.dtsi

Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Cc: Rob Herring <robh@kernel.org>
Reviewed-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>