x86/apic: Get rid of apic->target_cpus

The target_cpus() callback of the apic struct is not really useful. Some
APICs return cpu_online_mask and others cpus_all_mask. The latter is bogus
as it does not take holes in the cpus_possible_mask into account.

Replace it with cpus_online_mask which makes the most sense and remove the
callback.

The usage sites will be removed in a later step anyway, so get rid of it
now to have incremental changes.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Yu Chen <yu.c.chen@intel.com>
Acked-by: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rui Zhang <rui.zhang@intel.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Len Brown <lenb@kernel.org>
Link: https://lkml.kernel.org/r/20170913213154.070850916@linutronix.de

arch/x86/include/asm/apic.h

@@ -298,7 +298,6 @@ struct apic {
 	u32	irq_dest_mode;
 
 	/* Functions and data related to vector allocation */
-	const struct cpumask *(*target_cpus)(void);
 	void	(*vector_allocation_domain)(int cpu, struct cpumask *retmask,
 					    const struct cpumask *mask);
 	int	(*cpu_mask_to_apicid)(const struct cpumask *cpumask,
@@ -484,8 +483,6 @@ static inline unsigned int read_apic_id(void)
 	return apic->get_apic_id(reg);
 }
 
-extern const struct cpumask *default_target_cpus(void);
-extern const struct cpumask *online_target_cpus(void);
 extern int default_apic_id_valid(int apicid);
 extern int default_acpi_madt_oem_check(char *, char *);
 extern void default_setup_apic_routing(void);