i2c: mxc_i2c: Remove i2c_idle_bus from probe

i2c_idle_bus is already used in i2c_init_transfer. So before each transfer
if the bus is not ready, the i2c_idle_bus will be used to force idle.
It is unnecessary to call it again in probe.

We found a issue when enabling i2c mux with the mxc_i2c. The mxc_i2c is probed
after mux probing. However, at this moment the mux is still in idle state not
select any port. So if we call i2c_idle_bus in probe, it will fail and cause
mxc_i2c probe failed.

Signed-off-by: Ye Li <ye.li@nxp.com>