ARM: i.MX6: call ksz9021 phy fixup for all i.MX6 boards

In current U-Boot the sabrelite, nitrogen6x and titanium all need
the same fixup for the ksz9021 phy. Instead of limiting the fixup
to a single board apply them for all.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>