net: fsl_enetc: fix the duplex setting on the iMX platform

net: fsl_enetc: fix the duplex setting on the iMX platform

The iMX and LS platforms use different bits in the same register to
set duplex, but their logics are opposite.
The current settings will result in unexpected configurations in
RGMII mode.

Fixes: e6df2f5e22c6 ("net: fsl_enetc: Update enetc driver to support i.MX95")
Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
Signed-off-by: Alice Guo <alice.guo@nxp.com>
Reviewed-by: Tim Harvey <tharvey@gateworks.com>