net: phy: shrink PHY settings array

The definition of array settings[] is quite lengthy meanwhile. Add a
macro to shrink the definition.

v2:
- Fix an indentation issue

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>