Makefile: refactor a little

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

Makefile

@@ -65,11 +65,9 @@ endif
 # the object files are placed in the source directory.
 #
 
-ifdef O
 ifeq ("$(origin O)", "command line")
 BUILD_DIR := $(O)
 endif
-endif
 
 # Call a source code checker (by default, "sparse") as part of the
 # C compilation.
@@ -614,7 +612,7 @@ SYSTEM_MAP = \
 		grep -v '\(compiled\)\|\(\.o$$\)\|\( [aUw] \)\|\(\.\.ng$$\)\|\(LASH[RL]DI\)' | \
 		LC_ALL=C sort
 $(obj)System.map:	$(obj)u-boot
-		@$(call SYSTEM_MAP,$<) > $(obj)System.map
+		@$(call SYSTEM_MAP,$<) > $@
 
 checkthumb:
 	@if test $(call cc-version) -lt 0404; then \

spl/Makefile

@@ -166,8 +166,7 @@ all:	$(ALL-y)
 
 ifdef CONFIG_SAMSUNG
 $(obj)$(BOARD)-spl.bin: $(obj)u-boot-spl.bin
-	$(OBJTREE)/tools/mk$(BOARD)spl \
-		$(obj)u-boot-spl.bin $(obj)$(BOARD)-spl.bin
+	$(OBJTREE)/tools/mk$(BOARD)spl $< $@
 endif
 
 $(obj)$(SPL_BIN).bin:	$(obj)$(SPL_BIN)