[ARM] Orion: instantiate the dsa switch driver

This adds DSA switch instantiation hooks to the orion5x and the
kirkwood ARM SoC platform code, and instantiates the DSA switch
driver on the 88F5181L FXO RD, the 88F5181L GE RD, the 6183 AP GE
RD, the Linksys WRT350n v2, and the 88F6281 RD boards.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Tested-by: Nicolas Pitre <nico@marvell.com>
Tested-by: Peter van Valderen <linux@ddcrew.com>
Tested-by: Dirk Teurlings <dirk@upexia.nl>
Signed-off-by: Nicolas Pitre <nico@marvell.com>