clk: eyeq: use the auxiliary device creation helper

clk: eyeq: use the auxiliary device creation helper

The auxiliary device creation of this driver is simple enough to
use the available auxiliary device creation helper.

Use it and remove some boilerplate code.

Tested-by: Théo Lebrun <theo.lebrun@bootlin.com>  # On Mobileye EyeQ5
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>