Due to a oversight in testing, the initialization of the recently
introduced Freescale I2C DM driver works only for 36 bit mode of e.g.
the MPC85XX SoCs (specifically, if the physical addresses are 64 bit
wide and the DT addresses 32 bit wide).

This patch corrects the initialization so that it will work in a more
general setting.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
Reviewed-by: York Sun <york.sun@nxp.com>