x86/include: address MISRA C:2012 Rule 5.3.

Variable 'mpc_default_type' in 'xen/arch/x86/include/asm/mpspec.h'
has no uses and causes shadowing with function parameter names
in 'mpparse.c'. Therefore, it is removed.

No functional changes.

Signed-off-by: Nicola Vetrini <nicola.vetrini@bugseng.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/include/asm/mpspec.h

@@ -15,7 +15,6 @@ extern void get_smp_config (void);
 extern unsigned char apic_version [MAX_APICS];
 extern int mp_irq_entries;
 extern struct mpc_config_intsrc mp_irqs [MAX_IRQ_SOURCES];
-extern int mpc_default_type;
 extern unsigned long mp_lapic_addr;
 extern bool pic_mode;