Blackfin: add init.elf helper code

This creates a standalone ELF that executes just the Blackfin initcode.
This is useful for people who want to program the low level aspects of
the CPU (memory/clocks/etc...) and can easily be used with JTAG for
quick booting while developing.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/arch/blackfin/cpu/Makefile b/arch/blackfin/cpu/Makefile
index df10f1b..5deaa9e 100644
--- a/arch/blackfin/cpu/Makefile
+++ b/arch/blackfin/cpu/Makefile
@@ -13,7 +13,7 @@
 
 LIB	= $(obj)lib$(CPU).o
 
-EXTRA    :=
+EXTRA    := init.elf
 CEXTRA   := initcode.o
 SEXTRA   := start.o
 SOBJS    := interrupt.o cache.o
@@ -61,6 +61,11 @@
 	fi
 endif
 
+$(obj)init.lds: init.lds.S
+	$(CPP) $(CPPFLAGS) $(LDPPFLAGS) -ansi -D__ASSEMBLY__ -P $^ -o $@
+$(obj)init.elf: $(obj)init.lds $(obj)init.o $(obj)initcode.o
+	$(LD) $(LDFLAGS) -T $^ -o $@
+
 #########################################################################
 
 # defines $(obj).depend target