drm/amdkfd: Remove the requirement for atomic Ops on vg20

Firmware have the workaround to replace the atomic Ops with read-modify-write on CP side.
User should not expect atomic Ops on system memory works normally if system didn't not
support it.

Signed-off-by: Shaoyun Liu <Shaoyun.Liu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-By: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -247,7 +247,7 @@ static const struct kfd_device_info vega20_device_info = {
 	.mqd_size_aligned = MQD_SIZE_ALIGNED,
 	.supports_cwsr = true,
 	.needs_iommu_device = false,
-	.needs_pci_atomics = true,
+	.needs_pci_atomics = false,
 	.num_sdma_engines = 2,
 	.num_sdma_queues_per_engine = 8,
 };