Switch to automatically generated CHANGELOG file.

(use "make CHANGELOG" to update it from time to time)

Makefile

@@ -318,6 +318,9 @@ $(obj)System.map:	$(obj)u-boot
 		grep -v '\(compiled\)\|\(\.o$$\)\|\( [aUw] \)\|\(\.\.ng$$\)\|\(LASH[RL]DI\)' | \
 		sort > $(obj)System.map
 
+CHANGELOG:
+	git log --no-merges U-Boot-1_1_5.. > $@
+
 #########################################################################
 else
 all $(obj)u-boot.hex $(obj)u-boot.srec $(obj)u-boot.bin \