drivers: net: fsl_enetc: move PCS and PHY config to probe

This reduces the time needed to establish a link as we don't reset the link
each time the interface is used.  Our Link capabilities do not change at
run-time so there is no need to re-apply PHY configuration each time.

Signed-off-by: Alex Marginean <alexandru.marginean@nxp.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>