parisc: add missing TI_TASK macro in syscall.S

LDREG 0(%r1),%r1 really wants to be accessing thread_info.task,
instead of hardcoding the 0.
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

arch/parisc/kernel/syscall.S

@@ -355,7 +355,7 @@ tracesys_exit:
 
 tracesys_sigexit:
 	ldo     -THREAD_SZ_ALGN-FRAME_SIZE(%r30),%r1      /* get task ptr */
-	LDREG	0(%r1), %r1
+	LDREG	TI_TASK(%r1), %r1
 #ifdef CONFIG_64BIT
 	ldo	-16(%r30),%r29			/* Reference param save area */
 #endif