drm/amdkfd: disable IOMMUv2 support for Raven

Use the dGPU path instead.  There were a lot of platform
issues with IOMMU in general on these chips due to windows
not enabling IOMMU at the time.  The dGPU path has been
used for a long time with newer APUs and works fine.  This
also paves the way to simplify the driver significantly.
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Tested-by: Mike Lothian <mike@fireburn.co.uk>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdkfd/kfd_device.c

@@ -194,11 +194,6 @@ static void kfd_device_info_init(struct kfd_dev *kfd,
 
 		kfd_device_info_set_event_interrupt_class(kfd);
 
-		/* Raven */
-		if (gc_version == IP_VERSION(9, 1, 0) ||
-		    gc_version == IP_VERSION(9, 2, 2))
-			kfd->device_info.needs_iommu_device = true;
-
 		if (gc_version < IP_VERSION(11, 0, 0)) {
 			/* Navi2x+, Navi1x+ */
 			if (gc_version == IP_VERSION(10, 3, 6))
@@ -292,7 +287,6 @@ struct kfd_dev *kgd2kfd_probe(struct amdgpu_device *adev, bool vf)
 			gfx_target_version = 90000;
 			f2g = &gfx_v9_kfd2kgd;
 			break;
-#ifdef KFD_SUPPORT_IOMMU_V2
 		/* Raven */
 		case IP_VERSION(9, 1, 0):
 		case IP_VERSION(9, 2, 2):
@@ -300,7 +294,6 @@ struct kfd_dev *kgd2kfd_probe(struct amdgpu_device *adev, bool vf)
 			if (!vf)
 				f2g = &gfx_v9_kfd2kgd;
 			break;
-#endif
 		/* Vega12 */
 		case IP_VERSION(9, 2, 1):
 			gfx_target_version = 90004;