dt-bindings: imx-lpi2c: Remove mx8dv compatible entry

mx8dv never entered into production and there is no other place
in the kernel referring to this SoC, so remove it from the
dt bindings documentation.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>