mx51evk: Remove unused SOBJS

There is no .S file in this directory, so just remove SOBJS.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
diff --git a/board/freescale/mx51evk/Makefile b/board/freescale/mx51evk/Makefile
index 470588e..224eaa3 100644
--- a/board/freescale/mx51evk/Makefile
+++ b/board/freescale/mx51evk/Makefile
@@ -25,12 +25,11 @@
 
 COBJS	:= mx51evk.o
 
-SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
+SRCS	:= $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(COBJS))
-SOBJS	:= $(addprefix $(obj),$(SOBJS))
 
-$(LIB):	$(obj).depend $(OBJS) $(SOBJS)
-	$(call cmd_link_o_target, $(OBJS) $(SOBJS))
+$(LIB):	$(obj).depend $(OBJS)
+	$(call cmd_link_o_target, $(OBJS))
 
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