net: mdio: mux-meson-g12a: use devm_clk_get_enabled to simplify the code

Use devm_clk_get_enabled() to simplify the code.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>