net: phy: at803x: stop switching phy delay config needlessly

This driver does a funny dance disabling and re-enabling
RX and/or TX delays. In any of the RGMII-ID modes, it first
disables the delays, just to re-enable them again right
away. This looks like a needless exercise.

Just enable the respective delays when in any of the
relevant 'id' modes, and disable them otherwise.

Also, remove comments which don't add anything that can't be
seen by looking at the code.

Signed-off-by: André Draszik <git@andred.net>
CC: Andrew Lunn <andrew@lunn.ch>
CC: Florian Fainelli <f.fainelli@gmail.com>
CC: Heiner Kallweit <hkallweit1@gmail.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>