ARM: dts: imx6q: skov: fix ethernet clock regression

A regression was introduced in the Skov specific i.MX6 flavor
reve-mi1010ait-1cp1 device tree causing the external ethernet controller
to not being selected as the clock source for the i.MX6 ethernet MAC,
resulting in a none functional ethernet interface. The root cause is
that the ethernet clock selection is now part of the clocks node, which
is overwritten in the specific device tree and wasn't updated to contain
these ethernet clocks.

Fixes: c8961407 ("ARM: dts: imx6qdl-skov-cpu: configure ethernet reference clock parent")
Signed-off-by: Stefan Kerkmann <s.kerkmann@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>