Blackfin arch: add proper ENDPROC()

add proper ENDPROC() to close out assembly functions
so size/type is set properly in the final ELF image

Signed-off-by: Mike Frysinger <michael.frysinger@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

diff --git a/arch/blackfin/lib/memcpy.S b/arch/blackfin/lib/memcpy.S
index c1e00ef..34b5a91 100644
--- a/arch/blackfin/lib/memcpy.S
+++ b/arch/blackfin/lib/memcpy.S
@@ -140,3 +140,5 @@
 	B[P0--] = R1;
 
 	RTS;
+
+ENDPROC(_memcpy)