UPSTREAM: iommu/rockchip: Reconstruct to support multi slaves

UPSTREAM: iommu/rockchip: Reconstruct to support multi slaves

There are some IPs, such as video encoder/decoder, contains 2 slave iommus,
one for reading and the other for writing. They share the same irq and
clock with master.

This patch reconstructs to support this case by making them share the same
Page Directory, Page Tables and even the register operations.
That means every instruction to the reading MMU registers would be
duplicated to the writing MMU and vice versa.

Change-Id: I3fd473898274cffcfb46c907b34bd3a4adc29250
Signed-off-by: ZhengShunQian <zhengsq@rock-chips.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Simon <xxm@rock-chips.com>
Signed-off-by: Mark Yao <mark.yao@rock-chips.com>
(cherry picked from commit cd6438c5f8446691afa4829fe1a9d7b656204f11)