iommu/mediatek: Reduce the tlb flush timeout value

Reduce the tlb timeout value from 100000us to 1000us. The original value
would make the kernel stuck for 100 ms with interrupts disabled, which
could have other side effects. The flush is expected to always take much
less than 1 ms, so use that instead.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>