drm/radeon: add set_uvd_clocks callback for ON/LN/TN (v4)

v2: write clk registers only once!
v3: update cg scratch register properly
v4: add TN support

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>