s390/kprobes: have more correct if statement in s390_get_insn_slot()

When checking the insn address wether it is a kernel image or module
address it should be an if-else-if statement not two independent if
statements.
This doesn't really fix a bug, but matches s390_free_insn_slot().
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/kprobes.c

@@ -252,7 +252,7 @@ static int __kprobes s390_get_insn_slot(struct kprobe *p)
 	p->ainsn.insn = NULL;
 	if (is_kernel_addr(p->addr))
 		p->ainsn.insn = get_dmainsn_slot();
-	if (is_module_addr(p->addr))
+	else if (is_module_addr(p->addr))
 		p->ainsn.insn = get_insn_slot();
 	return p->ainsn.insn ? 0 : -ENOMEM;
 }