iommu: dart: Add suspend/resume support

iommu: dart: Add suspend/resume support

[ Upstream commit 34d8bb9b5a6a6ad53ffa014e5871daeb99eef598 ]

We need to save/restore the TCR/TTBR registers, since they are lost
on power gate.

Reviewed-by: Sven Peter <sven@svenpeter.dev>
Signed-off-by: Hector Martin <marcan@marcan.st>
Link: https://lore.kernel.org/r/20230113105029.26654-3-marcan@marcan.st
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Stable-dep-of: fd020c6741d5 ("iommu/dart: Fix apple_dart_device_group for PCI groups")
Signed-off-by: Sasha Levin <sashal@kernel.org>