i2c: mxc: Fix dev_err being called on a nonexistant variable

The udevice we are working with is called `bus` and not `dev`.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>
Tested-by: Patrick Delaunay <patrick.delaunay@st.com>
1 file changed