s390/perf: fix compile error (undefined reference sie_exit)

The perf_event code references sie_exit even if KVM is not available.
So add proper ifdefs to fix this one:

arch/s390/built-in.o: In function `sys_call_table_emu':
(.rodata+0x2b98): undefined reference to `sie_exit'
arch/s390/built-in.o: In function `sys_call_table_emu':
(.rodata+0x2ba0): undefined reference to `sie_exit'
make: *** [vmlinux] Error 1
Reported-by: Zhouping Liu <zliu@redhat.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/perf_event.c

@@ -52,12 +52,13 @@ static struct kvm_s390_sie_block *sie_block(struct pt_regs *regs)
 
 static bool is_in_guest(struct pt_regs *regs)
 {
-	unsigned long ip = instruction_pointer(regs);
-
 	if (user_mode(regs))
 		return false;
-
-	return ip == (unsigned long) &sie_exit;
+#if defined(CONFIG_KVM) || defined(CONFIG_KVM_MODULE)
+	return instruction_pointer(regs) == (unsigned long) &sie_exit;
+#else
+	return false;
+#endif
 }
 
 static unsigned long guest_is_user_mode(struct pt_regs *regs)