x86: Suppress empty cpumask ipi warning

We know already which code pathes trigger this so we can safely
disable it again and just keep the early return when mask == 0.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/apic/ipi.c

@@ -106,7 +106,7 @@ void default_send_IPI_mask_logical(const struct cpumask *cpumask, int vector)
 	unsigned long mask = cpumask_bits(cpumask)[0];
 	unsigned long flags;
 
-	if (WARN_ONCE(!mask, "empty IPI mask"))
+	if (!mask)
 		return;
 
 	local_irq_save(flags);