drm/amdgpu: Surface svm_default_granularity, a RW module parameter

Enables users to update SVM's default granularity, used in
buffer migration and handling of recoverable page faults.
Param value is set in terms of log(numPages(buffer)),
e.g. 9 for a 2 MIB buffer

Signed-off-by: Ramesh Errabolu <Ramesh.Errabolu@amd.com>
Reviewed-by: Philip Yang <Philip.Yang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdkfd/kfd_priv.h

@@ -868,6 +868,12 @@ struct svm_range_list {
 	struct task_struct		*faulting_task;
 	/* check point ts decides if page fault recovery need be dropped */
 	uint64_t			checkpoint_ts[MAX_GPU_INSTANCE];
+
+	/* Default granularity to use in buffer migration
+	 * and restoration of backing memory while handling
+	 * recoverable page faults
+	 */
+	uint8_t default_granularity;
 };
 
 /* Process data */