i2c: imx: use exact SoC revision to document binding

use exact SoC revision instead of wildcard describing
the compatible property requirement in the binding
document. This will make the binding more clearer.

Signed-off-by: Jingchang Lu <b35083@freescale.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>