drm/amdkfd: Fix ATS capablity was not reported correctly on some APUs

drm/amdkfd: Fix ATS capablity was not reported correctly on some APUs

Because CRAT_CU_FLAGS_IOMMU_PRESENT was not set in some BIOS crat, we
need to workaround this.

For future compatibility, we also overwrite the bit in capability according
to the value of needs_iommu_device.

Acked-by: Alex Deucher <[email protected]>
Signed-off-by: Yong Zhao <[email protected]>
Reviewed-by: Felix Kuehling <[email protected]>
Signed-off-by: Felix Kuehling <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>