sxgbe: remove unused code

Remove the unused code of sxgbe_xpcs.

Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Suggested-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jean Sacren <sakiwit@gmail.com>
Cc: Byungho An <bh74.an@samsung.com>
Cc: Girish K S <ks.giri@samsung.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1601191918470.2531@hadrien
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/samsung/sxgbe/Makefile

@@ -1,4 +1,4 @@
 obj-$(CONFIG_SXGBE_ETH) += samsung-sxgbe.o
 samsung-sxgbe-objs:= sxgbe_platform.o sxgbe_main.o sxgbe_desc.o \
 		sxgbe_dma.o sxgbe_core.o sxgbe_mtl.o  sxgbe_mdio.o \
-		sxgbe_ethtool.o sxgbe_xpcs.o $(samsung-sxgbe-y)
+		sxgbe_ethtool.o $(samsung-sxgbe-y)