Instead take the callback lock during the final parts of CS.

This should solve the last remaining locking order problems with BO reservations.

v2: rebase, make dummy functions static inline
v3: add one more missing inline and comments
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>