iommu/arm-smmu-v3: Don't disable SMMU in kdump kernel

iommu/arm-smmu-v3: Don't disable SMMU in kdump kernel

[ Upstream commit 3f54c447df34ff9efac7809a4a80fd3208efc619 ]

Disabling the SMMU when probing from within a kdump kernel so that all
incoming transactions are terminated can prevent the core of the crashed
kernel from being transferred off the machine if all I/O devices are
behind the SMMU.

Instead, continue to probe the SMMU after it is disabled so that we can
reinitialise it entirely and re-attach the DMA masters as they are reset.
Since the kdump kernel may not have drivers for all of the active DMA
masters, we suppress fault reporting to avoid spamming the console and
swamping the IRQ threads.

Reported-by: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
Tested-by: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
Tested-by: Bhupesh Sharma <bhsharma@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>