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/memchr.S b/arch/blackfin/lib/memchr.S
index 4981222..5da4281 100644
--- a/arch/blackfin/lib/memchr.S
+++ b/arch/blackfin/lib/memchr.S
@@ -67,4 +67,4 @@
 	R0 += -1;
 	RTS;
 
-.size _memchr,.-_memchr
+ENDPROC(_memchr)