For migration start and end event, output timestamp when migration
starts, ends, svm range address and size, GPU id of migration source and
destination and svm range attributes,

Migration trigger could be prefetch, CPU or GPU page fault and TTM
eviction.
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>