s390/unwind: drop unnecessary code around calling ftrace_graph_ret_addr()

The current code around calling ftrace_graph_ret_addr() is ifdeffed and
also tests if ftrace redirection is present on stack.
ftrace_graph_ret_addr() however performs the test internally and there
is a version for !CONFIG_FUNCTION_GRAPH_TRACER as well. The unnecessary
code can thus be dropped.

Link: http://lkml.kernel.org/r/20191029143904.24051-2-mbenes@suse.czSigned-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/kernel/unwind_bc.c

@@ -80,12 +80,7 @@ bool unwind_next_frame(struct unwind_state *state)
 		}
 	}
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	/* Decode any ftrace redirection */
-	if (ip == (unsigned long) return_to_handler)
-		ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-					   ip, (void *) sp);
-#endif
+	ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, (void *) sp);
 
 	/* Update unwind state */
 	state->sp = sp;
@@ -140,12 +135,7 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
 		reliable = false;
 	}
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
-	/* Decode any ftrace redirection */
-	if (ip == (unsigned long) return_to_handler)
-		ip = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-					   ip, NULL);
-#endif
+	ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, NULL);
 
 	/* Update unwind state */
 	state->sp = sp;