s390/ftrace: remove preempt_disable()/preempt_enable() pair

It looks like commit ce5e480 ("ftrace: disable preemption
when recursion locked") missed a spot in kprobe_ftrace_handler() in
arch/s390/kernel/ftrace.c.
Remove the superfluous preempt_disable/enable_notrace() there too.

Fixes: ce5e480 ("ftrace: disable preemption when recursion locked")
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Link: https://lore.kernel.org/r/20211208151503.1510381-1-jmarchan@redhat.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/kernel/ftrace.c

@@ -290,7 +290,6 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 		return;
 
 	regs = ftrace_get_regs(fregs);
-	preempt_disable_notrace();
 	p = get_kprobe((kprobe_opcode_t *)ip);
 	if (unlikely(!p) || kprobe_disabled(p))
 		goto out;
@@ -318,7 +317,6 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 	}
 	__this_cpu_write(current_kprobe, NULL);
 out:
-	preempt_enable_notrace();
 	ftrace_test_recursion_unlock(bit);
 }
 NOKPROBE_SYMBOL(kprobe_ftrace_handler);