ARM: OMAP AM3517/3505: clock data: change EMAC clocks aliases

Rename EMAC clocks to match driver expectations: both davinci_emac and
davinci_mdio drivers call clk_get(dev, NULL) so we have to provide
("davinci_emac", NULL) and ("davinci_mdio.0", NULL) clocks instead of
("davinci_emac", "emac_clk") and ("davinci_emac", "phy_clk") resp.

Cc: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Ilya Yanok <yanok@emcraft.com>
Tested-by: Yegor Yefremov <yegorslists@googlemail.com>
Tested-by: Matt Porter <mporter@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>