apic_bsp_setup() sets and returns logical APIC ID for initializing
cpu0_logical_apicid in a SMP-capable system.

The id has nothing to do with the initialization of local APIC and I/O
APIC. And apic_bsp_setup() should be called for interrupt mode setup only.

Move the id setup into a separate helper function for cleanup and mark
apic_bsp_setup() void.
Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: yinghai@kernel.org
Cc: bhe@redhat.com
Link: https://lkml.kernel.org/r/1505293975-26005-5-git-send-email-douly.fnst@cn.fujitsu.com