There are several issues with the dev_config union used as a
convenience when calling the i2c_configure api. One, the union is well
name spaced protected and doesn't convey use with just i2c. Second
there are assumptions of how the bits might get packed by the union
which can't be guaranteed. Since the API takes a u32_t lets change in
tree uses to using the macros to setup a u32_t and make the union as
deprecated.
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>