x86/mach-apic: Drop apic_id_registered()

It's an unnecessary wrapper.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/apic.c

@@ -495,8 +495,7 @@ void setup_local_APIC(bool bsp)
     /*
      * Double-check whether this APIC is really registered.
      */
-    if (!apic_id_registered())
-        BUG();
+    BUG_ON(!physid_isset(get_apic_id(), phys_cpu_present_map));
 
     /*
      * Intel recommends to set DFR, LDR and TPR before enabling

xen/arch/x86/include/asm/mach-generic/mach_apic.h

@@ -45,12 +45,6 @@ static inline int multi_timer_check(int apic, int irq)
  * really not sure why, since all local APICs should have distinct physical
  * IDs, and we need to know what they are.
  */
-static inline int apic_id_registered(void)
-{
-	return physid_isset(get_apic_id(),
-			    phys_cpu_present_map);
-}
-
 static inline void ioapic_phys_id_map(physid_mask_t *map)
 {
 	*map = phys_cpu_present_map;