Add the DT support for the I2C GPIO expander inside the twl4030.

Note: The pdata parameters still have to be properly adapted using
dedicated bindings.
Signed-off-by: NBenoit Cousson <b-cousson@ti.com>
Acked-by: NFelipe Balbi <balbi@ti.com>
Acked-by: NGrant Likely <grant.likely@secretlab.ca>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>