add smu_free_memory when smu fini to prevent memory leakage

v2: squash in typo fix (Yintian) and warning (Harry)
Signed-off-by: Yintian Tao <yttao@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>