irqchip/gic-v3-its: Remove superfluous WARN_ON

"ITS virtual pending table not cleaning" is already complained inside
its_clear_vpend_valid(), there's no need to trigger a WARN_ON again.
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200206075711.1275-6-yuzenghui@huawei.com

drivers/irqchip/irq-gic-v3-its.c

@@ -2857,7 +2857,6 @@ static void its_cpu_init_lpis(void)
 		 * corrupting memory.
 		 */
 		val = its_clear_vpend_valid(vlpi_base, 0, 0);
-		WARN_ON(val & GICR_VPENDBASER_Dirty);
 	}
 
 	if (allocate_vpe_l1_table()) {