net: dwc_eth_qos: Scrub ifdeffery

net: dwc_eth_qos: Scrub ifdeffery

Replace ifdef CONFIG_CLK with if (CONFIG_IS_ENABLED(CLK)) to improve code
build coverage. Some of the functions printed debug("%s: OK\n", __func__);
on exit with and without CLK enabled, some did not, make it consistent and
print nothing if CLK is disabled.

Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Christophe ROULLIER <christophe.roullier@foss.st.com>