ARM: orion: remove unused wnr854t_switch_plat_data

The other instances of this structure got removed along with the MDIO
device change, but this one was left behind and needs to be removed
as well:

arch/arm/mach-orion5x/wnr854t-setup.c:109:44: error: 'wnr854t_switch_plat_data' defined but not used [-Werror=unused-variable]
 static struct dsa_platform_data __initdata wnr854t_switch_plat_data = {

Fixes: 575e93f7 ("ARM: orion: Register DSA switch as a MDIO device")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>