NET: designware: fix clock enable

NET: designware: fix clock enable

After commit ba1f966725223 ("net: designware: add clock support")
we got NET broken on axs101 and axs103 platforms.

Some clock don't support gating so their clock drivers don't
implement .enable/.disable callbacks. In such case clk_enable
returns -ENOSYS.
Also some clock drivers implement .enable/.disable callbacks not for all
clock IDs and return -ENOSYS (or -ENOTSUPP) for others.

If we have such clock in 'clocks' list of designware ethernet controller
node we fail to probe designware ethernet.

Fix it.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>