net: phy: at803x: constify static regulator_ops

The only usage of vddio_regulator_ops and vddh_regulator_ops is to
assign their address to the ops field in the regulator_desc struct,
which is a const pointer. Make them const to allow the compiler to
put them in read-only memory.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>