net: dm: fec: Fix regulator enable when using DM_REGULATOR

net: dm: fec: Fix regulator enable when using DM_REGULATOR

When DM_REGULATOR is enabled, the driver attempts to call
regulator_autoset() which expects the regulators to be on at boot
and/or always on and fails if they are not true.
For a more generic approach, this patch just calls
regulator_set_enable() which shouldn't have such restrictions.

Fixes: ad8c43cbcafb ("net: dm: fec: Support the phy-supply
binding")

Signed-off-by: Adam Ford <aford173@gmail.com>
Tested-by: Martin Fuzzey <martin.fuzzey@flowbird.group>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>