phy/marvell: fix 88e1121 support

phy/marvell: fix 88e1121 support

commit be8c648051048bc66fbca590d00f3e8543ec32af upstream.

Commit c477d0447db08068a497e7beb892b2b2a7bff64b added support for RGMII
rx/tx delays except that it ends up clearing rx/tx delays bit for modes
differents that RGMII*ID. Due to this, ethernet is not working anymore
on my guruplug server +. This patch is fixing that.

Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>