Blackfin arch: add support for Blackfin latest processor family BF51x

Signed-off-by: Bryan Wu <cooloney@kernel.org>

diff --git a/arch/blackfin/mach-bf518/Makefile b/arch/blackfin/mach-bf518/Makefile
new file mode 100644
index 0000000..9d5e16d
--- /dev/null
+++ b/arch/blackfin/mach-bf518/Makefile
@@ -0,0 +1,7 @@
+#
+# arch/blackfin/mach-bf518/Makefile
+#
+
+extra-y := head.o
+
+obj-y := ints-priority.o dma.o