x86/apic: Remove duplicate X86_64 conditional in lapic_is_integrated()

The macro APIC_INTEGRATED(x) is already wrapped by CONFIG_X86_32. So
it can be invoked unconditionally.

Remove the extra "#ifdef CONFIG_X86_64...". No functional change.

Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: bhe@redhat.com
Link: https://lkml.kernel.org/r/1504774161-7137-1-git-send-email-douly.fnst@cn.fujitsu.com