mfd: Make pcf50633 suspend/resume belong to i2c_driver

When not using the i2c suspend/resume callbacks the i2c client resumed
before the i2c master.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>