drm/amd/pm: add interface to deallocate power_context for smu_v13_0_7

add interface to deallocate power_context for smu_v13_0_7

Signed-off-by: Kenneth Feng <kenneth.feng@amd.com>
Reviewed-by: Yang Wang <kevinyang.wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>