x86: Do not attempt to calibrate the LAPIC timer if no APIC is present

Reported and tested by:	Michael Butler <imb@protected-networks.net>
Reviewed by:	jhb, kib
Fixes:	62d09b46ad ("x86: Defer LAPIC calibration until after timecounters are available")
MFC after:	3 days
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D33669

sys/x86/x86/local_apic.c

@@ -913,6 +913,12 @@ native_lapic_calibrate_timer(void)
 	struct lapic *la;
 	register_t intr;
 
+#ifdef DEV_ATPIC
+	/* Fail if the local APIC is not present. */
+	if (!x2apic_mode && lapic_map == NULL)
+		return;
+#endif
+
 	intr = intr_disable();
 	la = &lapics[lapic_id()];