irqchip/gic-v4.1: Reduce the delay when polling GICR_VPENDBASER.Dirty

The 10us delay of the poll on the GICR_VPENDBASER.Dirty bit is too
high, which might greatly affect the total scheduling latency of a
vCPU in our measurement. So we reduce it to 1 to lessen the impact.
Signed-off-by: Shenming Lu <lushenming@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201128141857.983-2-lushenming@huawei.com

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

@@ -3808,7 +3808,7 @@ static void its_wait_vpt_parse_complete(void)
 	WARN_ON_ONCE(readq_relaxed_poll_timeout_atomic(vlpi_base + GICR_VPENDBASER,
 						       val,
 						       !(val & GICR_VPENDBASER_Dirty),
-						       10, 500));
+						       1, 500));
 }
 
 static void its_vpe_schedule(struct its_vpe *vpe)