common: Delete unnecessary rules.

The directory tools/ is always built before common/.
So when envcrc tool is necessary in common/Makefile,
it already exists.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/common/Makefile b/common/Makefile
index 32acbf9..74404be 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -232,14 +232,11 @@
 
 CPPFLAGS += -I..
 
-$(obj)env_embedded.o: $(src)env_embedded.c $(obj)../tools/envcrc
+$(obj)env_embedded.o: $(src)env_embedded.c
 	$(CC) $(AFLAGS) -Wa,--no-warn \
 		-DENV_CRC=$(shell $(obj)../tools/envcrc) \
 		-c -o $@ $(src)env_embedded.c
 
-$(obj)../tools/envcrc:
-	$(MAKE) -C ../tools
-
 # SEE README.arm-unaligned-accesses
 $(obj)hush.o: CFLAGS += $(PLATFORM_NO_UNALIGNED)
 $(obj)fdt_support.o: CFLAGS += $(PLATFORM_NO_UNALIGNED)