net: ti: icssg_prueth: Fix argument passed to icssg_update_rgmii_cfg()
icssg_update_mii_rt_cfg() accepts slice number as the 3rd argument
which indicate if it is for MII0 or MII1. So fix emac_adjust_link()
pass slice for link down case.
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>