net: dsa: microchip: move ksz_chip_id enum to platform include

With the ksz_chip_id enums moved to the platform include file for ksz
switches, platform code that instantiates a device can now use these to
set ksz_platform_data::chip_id.

Signed-off-by: Daniel Danzberger <dd@embedd.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>