dt-bindings: i2c: mpc: Mark "fsl,timeout" as deprecated

Now we have the i2c-scl-clk-low-timeout-us property defined in
the i2c schema.

Mark "fsl,timeout" as deprecated and update the example.

Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>