net: sh_eth: fix TX/RX descriptor not set physical memory

Fix the probrem that TX/RX descirptor not set physical memory.

Signed-off-by: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu.nobuhiro@renesas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>