x86/platform/uv: Use apic_ack_irq()

To address the EBUSY fail of interrupt affinity settings in case that the
previous setting has not been cleaned up yet, use the new apic_ack_irq()
function instead of the special uv_ack_apic() implementation which is
merily a wrapper around ack_APIC_irq().

Preparatory change for the real fix

Fixes: dccfe314 ("x86/vector: Simplify vector move cleanup")
Reported-by: Song Liu <liu.song.a23@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Song Liu <songliubraving@fb.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: stable@vger.kernel.org
Cc: Mike Travis <mike.travis@hpe.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Tariq Toukan <tariqt@mellanox.com>
Link: https://lkml.kernel.org/r/20180604162224.721691398@linutronix.de