xtensa_dumpstate.c: Fix the name of the TCB variable when dumping the

backtrace.

Signed-off-by: Abdelatif Guettouche <abdelatif.guettouche@espressif.com>

arch/xtensa/src/common/xtensa_dumpstate.c

@@ -74,7 +74,7 @@ static void up_taskdump(FAR struct tcb_s *tcb, FAR void *arg)
 
 #if defined(CONFIG_XTENSA_DUMPBT_ON_ASSERT) && \
     defined(CONFIG_SCHED_BACKTRACE)
-  sched_dumpstack(rtcb->pid);
+  sched_dumpstack(tcb->pid);
 #endif
 }
 #endif