net: thunderx: start phy before starting autonegotiation

Since commit 2b3e88ea ("net: phy: improve phy state checking")
phy_start_aneg() expects phy state to be >= PHY_UP. Call phy_start()
before calling phy_start_aneg() during probe so that autonegotiation
is initiated.

As phy_start() takes care of calling phy_start_aneg(), drop the explicit
call to phy_start_aneg().

Network fails without this patch on Octeon TX.

Fixes: 2b3e88ea ("net: phy: improve phy state checking")
Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>