powerpc/xmon: fix task state output

p_state is unsigned since the commit 2f064a5

The patch also uses TASK_RUNNING instead of null.

Fixes: 2f064a5 ("sched: Change task_struct::state")
Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211026133108.7113-1-kda@linux-powerpc.org

arch/powerpc/xmon/xmon.c

@@ -3264,8 +3264,7 @@ static void show_task(struct task_struct *volatile tsk)
 	 * appropriate for calling from xmon. This could be moved
 	 * to a common, generic, routine used by both.
 	 */
-	state = (p_state == 0) ? 'R' :
-		(p_state < 0) ? 'U' :
+	state = (p_state == TASK_RUNNING) ? 'R' :
 		(p_state & TASK_UNINTERRUPTIBLE) ? 'D' :
 		(p_state & TASK_STOPPED) ? 'T' :
 		(p_state & TASK_TRACED) ? 'C' :