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/.gitignore b/arch/blackfin/cpu/.gitignore
index 0ec9d56..ba986d8 100644
--- a/arch/blackfin/cpu/.gitignore
+++ b/arch/blackfin/cpu/.gitignore
@@ -1 +1,4 @@
 bootrom-asm-offsets.[chs]
+
+init.lds
+init.elf