drivers: net: dsa: remove duplicate includes

These duplicate includes have been found with scripts/checkincludes.pl but
they have been removed manually to avoid removing false positives.
Signed-off-by: NPravin Shedge <pravin.shedge4linux@gmail.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/dsa/bcm_sf2.c

@@ -14,7 +14,6 @@
 #include <linux/netdevice.h>
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
-#include <linux/of.h>
 #include <linux/phy.h>
 #include <linux/phy_fixed.h>
 #include <linux/mii.h>