dpm: deepsleep: reserve stack

Reserve 12 bytes on the stack for deepsleep use.
Signed-off-by: Steven Miao <realmz6@gmail.com>
Signed-off-by: Bob Liu <lliubbo@gmail.com>

arch/blackfin/mach-bf609/dpm.S

@@ -69,7 +69,7 @@ ENTRY(_dummy_deepsleep)
 ENDPROC(_dummy_deepsleep)
 
 ENTRY(_enter_deepsleep)
-	LINK 0x0;
+	LINK 0xC;
 	[--sp] = (R7:0,P5:0);
 
 	/* Change EVT 11 entry to dummy handler for wake up event */