In order to easier inform the user that the driver has been initialized
successfully, add a printout after the driver has been initialized.

At the same time, remove a dev_dbg() that is now redundant.
Signed-off-by: Niklas Cassel <nks@flawful.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>