iommu/arm-smmu: Emulate bypass by using context banks

Some firmware found on various Qualcomm platforms traps writes to S2CR
of type BYPASS and writes FAULT into the register. This prevents us from
marking the streams for the display controller as BYPASS to allow
continued scanout of the screen through the initialization of the ARM
SMMU.

This adds a Qualcomm specific cfg_probe function, which probes the
behavior of the S2CR registers and if found faulty enables the related
quirk. Based on this quirk context banks are allocated for IDENTITY
domains as well, but with ARM_SMMU_SCTLR_M omitted.

The result is valid stream mappings, without translation.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Message-Id: <20200709050145.3520931-3-bjorn.andersson@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>