net: dsa: microchip: Factor out regmap config generation into common header

The regmap config tables are rather similar for various generations of
the KSZ8xxx/KSZ9xxx switches. Introduce a macro which allows generating
those tables without duplication. Note that $regalign parameter is not
used right now, but will be used in KSZ87xx series switches.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Tristram Ha <Tristram.Ha@microchip.com>
Cc: Woojung Huh <Woojung.Huh@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>