alpha: merge build rules of division routines

These four objects are generated by the same build rule, with
different compile options.  The build rules can be merged.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

arch/alpha/lib/Makefile

@@ -46,11 +46,6 @@ AFLAGS___remqu.o =       -DREM
 AFLAGS___divlu.o = -DDIV       -DINTSIZE
 AFLAGS___remlu.o =       -DREM -DINTSIZE
 
-$(obj)/__divqu.o: $(src)/$(ev6-y)divide.S
-	$(cmd_as_o_S)
-$(obj)/__remqu.o: $(src)/$(ev6-y)divide.S
-	$(cmd_as_o_S)
-$(obj)/__divlu.o: $(src)/$(ev6-y)divide.S
-	$(cmd_as_o_S)
-$(obj)/__remlu.o: $(src)/$(ev6-y)divide.S
+$(addprefix $(obj)/,__divqu.o __remqu.o __divlu.o __remlu.o): \
+							$(src)/$(ev6-y)divide.S
 	$(cmd_as_o_S)